Tropical Storm Fay is inland and did do some damage.
There have been a few tornadoes with some cars overturned in Stuart, FL. (Martin County)
The storm will slowly drift north and plaque northern Florida, southern Georgia and portions of Alabama over the next 5 days.
Fay may actually move into the Atlantic side of Florida (near Orlando) and make a second landfall between Daytona and Jacksonville sometime of Thursday. Or even on the Georgia coast.
There isn't really any major weather feature to steer the storm so the actual track remains very undefined at this time.
It isn't all bad news however -- remember this part of the world really needs the rainfall, especially Georgia and Alabama and vicinity.
So Fay could be a blessing but could also be an unwanted pest if she lingers for several days.
Just keep up with all the latest forecasts if you live or need to travel to this region over the next few days.
Did you see the Florida map today on CoCoRaHS? Wow a lot of rain, with over 8 inches from one observer near Sun Valley in Palm Beach County. (north of Ft. Lauderdale/Miami area)
Another observer in the same county had 7.64 inches.
Amazing to me! I am sure I experienced that at some point during my 19 years in Arkansas, but after living in the high deserts of Colorado for so long now -- when I think of 8 inches of rain if it fell here, I see widespread destruction.
Denver's annual precipitation (including rain and melted snow) is just a little over 15 inches.
Today's Weather Lesson
Ok it's been a few days since our last lesson when we talked about energy, both potential and kinetic.
There is a law you learn in science about energy that states energy is neither created nor destroyed. It merely changes from one form to another.
Temperature is a measure of the average kinetic energy (or speed) of all the atoms and molecules in the atmosphere, where higher temperatures mean faster average speeds and colder temperatures mean slower speeds.
The warmer the air, the further apart the molecules are, so it is less dense and rises.
The colder the air, the closer the molecules are, so it is more dense and sinks.
Temperature tells you how hot or cold something is relative to a set standard value.
Another type of energy we hear about it called heat. This is the energy being transferred from one object to another due to a temperature difference between the two objects.
Once heat is transferred, it is stored as internal energy.
In the atmosphere, heat is transferred by conduction, convection and radiation.
Tomorrow we'll discuss temperature scales and some important types of heat to weather. (latent heat and specific heat)
CoCoRaHS
Tuesday, August 19, 2008
Monday, August 18, 2008
Tropical Storm Fay
Well Fay has survived her journey over the island nations of the Caribbean, and is on a beeline for Florida.
It will impact the entire state with rain and wind over the next 48 hours, but the brunt will likely be felt along the southwest coast between Ft. Myers and Tampa.
Fay could become a minimal hurricane (cat. 1 or 2) which to those who live in hurricane territory, isn't feared like a major hurricane, but a cat 1 or 2 can still do some serious damage from both wind and water.
So for all the CoCoRaHS observers in the Sunshine State -- the rest of us are sending you our best thoughts and will be anxiously awaiting to see your reports.
Attention Florida observers: Please leave detailed comments! Not only are they interesting to all of us, BUT they provide invaluable information to officials who recap the storm in detail.
But remember safety first!! Don't endanger your life to report to CoCoRaHS!
It will impact the entire state with rain and wind over the next 48 hours, but the brunt will likely be felt along the southwest coast between Ft. Myers and Tampa.
Fay could become a minimal hurricane (cat. 1 or 2) which to those who live in hurricane territory, isn't feared like a major hurricane, but a cat 1 or 2 can still do some serious damage from both wind and water.
So for all the CoCoRaHS observers in the Sunshine State -- the rest of us are sending you our best thoughts and will be anxiously awaiting to see your reports.
Attention Florida observers: Please leave detailed comments! Not only are they interesting to all of us, BUT they provide invaluable information to officials who recap the storm in detail.
But remember safety first!! Don't endanger your life to report to CoCoRaHS!
Saturday, August 16, 2008
Fay Forms, Potentially Florida Bound
Attention all CoCoRaHSians in Florida and along the eastern and central Gulf Coast --- keep your eye on Fay.
The disturbance that has been on the radar scope these past few days finally formed into an organized system, becoming the 6th named storm of the Atlantic Hurricane Season.
There are several wildcards in the forecast, including how Fay interacts with the higher terrain of Cuba, the subtropical high pressure over the western Atlantic and an approaching trough of low pressure.
Current model output has Fay moving west-northwest, then taking a turn north, moving over the Florida keys and paralleling the western coast of Florida, making landfall in the central Panhandle sometime during the middle of this coming week.
If that path comes true, it would give Fay the chance to really become a strong hurricane with the center staying over water, but the storm being close enough to really give the west coast of Florida a wallop.
One thing is for certain, it is pretty likely that Fay will impact the Gulf Coast states somewhere -- but exactly where, when and how strong are still a tough call.
If you live in these areas, have family there, or are traveling there over the next few days, keep a close eye on the forecast.
You can visit the National Hurricane Center's Web site for all the latest information.
Just click here.
The disturbance that has been on the radar scope these past few days finally formed into an organized system, becoming the 6th named storm of the Atlantic Hurricane Season.
There are several wildcards in the forecast, including how Fay interacts with the higher terrain of Cuba, the subtropical high pressure over the western Atlantic and an approaching trough of low pressure.
Current model output has Fay moving west-northwest, then taking a turn north, moving over the Florida keys and paralleling the western coast of Florida, making landfall in the central Panhandle sometime during the middle of this coming week.
If that path comes true, it would give Fay the chance to really become a strong hurricane with the center staying over water, but the storm being close enough to really give the west coast of Florida a wallop.
One thing is for certain, it is pretty likely that Fay will impact the Gulf Coast states somewhere -- but exactly where, when and how strong are still a tough call.
If you live in these areas, have family there, or are traveling there over the next few days, keep a close eye on the forecast.
You can visit the National Hurricane Center's Web site for all the latest information.
Just click here.
Friday, August 15, 2008
Overnight Thunderstorms
Well good morning from socked in Denver -- it's a balmy 50 degrees with heavy mist/fog.
Once I moved to Colorado I really began to miss the overnight thunderstorms I was used to in the east. We just don't see that too often here -- in fact -- I can count on my left hand how many times I have seen it here over the past 8 years.
Well last night was an exception, in fact, it was one of the best shows I have seen yet.
I woke up about 3:51 am thinking is that thunder? Then I saw the lightning once I focused my eyes and said yes it was. It grew more intense and a bolt hit somewhere very close to me shortly there after.
The thunder rattled my windows!!!
Me and my basset hound (Samson) just snuggled down in the center of the bed looking out the window.
I have been on vacation this week and landscaping my backyard -- I went to check my gauge at 7 am and thankfully the work I have done so far survived it's first thunderstorm!
Elsewhere, the CoCoRaHS national map is a busy one today with pockets of moderate to heavy rain recorded over the past 24 hours across eastern Colorado, SW Kansas, central Oklahoma, north-central Texas, much of Missouri and Indiana as well as central Florida.
It's hot in the CoCoRaHS state of Oregon with triple digit heat again in downtown Portland. They had a record high on Thursday of 101° -- it was 102° at the Portland airport.
Medford was 108°! It was even 100° in Eugene.
The tropics are heating up with that area of disturbed weather still around Puerto Rico -- it could become the next tropical system over the weekend.
We are nearing the peak of the Atlantic Hurricane Season so according to climatology things should get active over the next few weeks.
Today's Lesson
We'll talk more about energy today.
Any moving substance has energy of motion, or kinetic energy.
Mathematically, this is KE = 1/2*mv² -- in text that would be kinetic energy equals one half times mass times velocity squared.
So the faster something moves, the more kinetic energy it will have -- so a strong wind has more kinetic energy than a light breeze.
Since the amount of kinetic energy also involves the objects mass, a volume of air and a volume of water moving at the same speed will have different amounts of kinetic energy.
Which one will be highest?
The water -- because it has a greater mass.
So how does this relate to weather?
The atoms and molecules that comprise all matter have kinetic energy due to motion. This form of kinetic energy is often called heat energy.
One of the most important forms of heat energy related to weather and climate is the energy we receive from the sun -- radiant energy.
Once I moved to Colorado I really began to miss the overnight thunderstorms I was used to in the east. We just don't see that too often here -- in fact -- I can count on my left hand how many times I have seen it here over the past 8 years.
Well last night was an exception, in fact, it was one of the best shows I have seen yet.
I woke up about 3:51 am thinking is that thunder? Then I saw the lightning once I focused my eyes and said yes it was. It grew more intense and a bolt hit somewhere very close to me shortly there after.
The thunder rattled my windows!!!
Me and my basset hound (Samson) just snuggled down in the center of the bed looking out the window.
I have been on vacation this week and landscaping my backyard -- I went to check my gauge at 7 am and thankfully the work I have done so far survived it's first thunderstorm!
Elsewhere, the CoCoRaHS national map is a busy one today with pockets of moderate to heavy rain recorded over the past 24 hours across eastern Colorado, SW Kansas, central Oklahoma, north-central Texas, much of Missouri and Indiana as well as central Florida.
It's hot in the CoCoRaHS state of Oregon with triple digit heat again in downtown Portland. They had a record high on Thursday of 101° -- it was 102° at the Portland airport.
Medford was 108°! It was even 100° in Eugene.
The tropics are heating up with that area of disturbed weather still around Puerto Rico -- it could become the next tropical system over the weekend.
We are nearing the peak of the Atlantic Hurricane Season so according to climatology things should get active over the next few weeks.
Today's Lesson
We'll talk more about energy today.
Any moving substance has energy of motion, or kinetic energy.
Mathematically, this is KE = 1/2*mv² -- in text that would be kinetic energy equals one half times mass times velocity squared.
So the faster something moves, the more kinetic energy it will have -- so a strong wind has more kinetic energy than a light breeze.
Since the amount of kinetic energy also involves the objects mass, a volume of air and a volume of water moving at the same speed will have different amounts of kinetic energy.
Which one will be highest?
The water -- because it has a greater mass.
So how does this relate to weather?
The atoms and molecules that comprise all matter have kinetic energy due to motion. This form of kinetic energy is often called heat energy.
One of the most important forms of heat energy related to weather and climate is the energy we receive from the sun -- radiant energy.
Thursday, August 14, 2008
Somethin's A Brewin' In The Tropics
We may be dealing with the next tropical system in the Atlantic Basin over the next few days.
If so, it will be Tropical Storm Fay.
There is a large area of disturbed weather just east of Puerto Rico moving west. Regardless of if it organizes, it will bring heavy rain and wind to the island and surrounding locations, such as Hispaniola, over the next few days.
Hurricane hunters are flying through the storm today and we should know more later in the day.
Meanwhile, there was a second day of rain over much of the southeast. This time the heavy rain fell in a band from Mobile, Ala. and extending across southern Georgia and the Carolinas.
There was also a pocket of good rain over the lower Great Lakes, in and around Chicago, as well as over Kansas and Nebraska.
Elsewhere it was dry for the most part.
Today's Lesson
We are ready to dive into energy, temperature and heat.
Energy is the ability or capacity to do work on some form of matter. Matter is anything that has mass and takes up space.
If matter is either pushed, pulled or lifted over some distance, then work has been done.
The total amount of energy stored in any object determines how much work that object is capable of performing.
This is called potential energy because it represents the potential to do work.
It can be represented by a math equation.
PE = m x g x h
In words, that would be potential energy equals the object's mass (m), times the acceleration of gravity (g), times the objects height above the ground (h).
To relate this to weather, if you have a parcel of air at the surface and then one up in the air -- the one above the surface has more potential energy because it can sink and warm through a greater depth of the atmosphere than the parcel of air already at ground level.
I know this might be boring to some, or hard to understand. Others may love it.
Bare with me, I am just setting the stage so we can get into the fun things that pertain to weather, like convection and thermals.
If so, it will be Tropical Storm Fay.
There is a large area of disturbed weather just east of Puerto Rico moving west. Regardless of if it organizes, it will bring heavy rain and wind to the island and surrounding locations, such as Hispaniola, over the next few days.
Hurricane hunters are flying through the storm today and we should know more later in the day.
Meanwhile, there was a second day of rain over much of the southeast. This time the heavy rain fell in a band from Mobile, Ala. and extending across southern Georgia and the Carolinas.
There was also a pocket of good rain over the lower Great Lakes, in and around Chicago, as well as over Kansas and Nebraska.
Elsewhere it was dry for the most part.
Today's Lesson
We are ready to dive into energy, temperature and heat.
Energy is the ability or capacity to do work on some form of matter. Matter is anything that has mass and takes up space.
If matter is either pushed, pulled or lifted over some distance, then work has been done.
The total amount of energy stored in any object determines how much work that object is capable of performing.
This is called potential energy because it represents the potential to do work.
It can be represented by a math equation.
PE = m x g x h
In words, that would be potential energy equals the object's mass (m), times the acceleration of gravity (g), times the objects height above the ground (h).
To relate this to weather, if you have a parcel of air at the surface and then one up in the air -- the one above the surface has more potential energy because it can sink and warm through a greater depth of the atmosphere than the parcel of air already at ground level.
I know this might be boring to some, or hard to understand. Others may love it.
Bare with me, I am just setting the stage so we can get into the fun things that pertain to weather, like convection and thermals.
Wednesday, August 13, 2008
Unusual Storm System
A large area of low pressure has brought some very beneficial rain to states in the southeast, along with some cool air for this time of year.
It is unusual because this type of storm system is more common in the winter months.
Typically in the south cold fronts and areas of low pressure just don't happen in the summer. About the only hope for precipitaton is from a land-falling tropical system or your every day garden variety pop-up showers and thunderstorms that result from daytime heating and all the abundant moisture in the air.
I think just about every CoCoRaHS station in Alabama and Georgia reported rain on Tuesday.
This area really needed that type of widespread rainfall so I am glad that Mother Nature threw them a curve ball.
Speaking of curve balls, we have one coming down the east side of the Rockies this weekend.
Our highs here in Denver will struggle to reach 70 degrees on Friday and Saturday. Lows should be in the upper 40s and lower 50s.
Our mountains will see a rain/snow mix above the treeline -- which is approximately 11,000 feet.
Fall will be here before you know it -- see make the most of these late summer days.
Today's Lesson
If you love weather, then you want to live in the middle latitudes -- between about 30 and 50° N -- which happens to be where the United States is located.
It is in this region where most of the exciting weather is found as cold air moves down from the Arctic and warm air moves up from the Equator.
Big areas of low pressure (also called middle latitude cyclonic storms) sweep across the country along with a front and make for exciting times.
A front is an area where there is a sharp change in temperature, humidity and wind direction.
Every state in the union can boast an example -- but I think one of the better examples is Missouri -- since there is a major city on each side of the state.
If you were to look at a weather report and Kansas City was 75 degrees with a 38 degree dewpoint, and St. Louis was 90 degrees with a 65 degree dewpoint -- you could easily tell there was a cold front sitting somewhere in between.
On one side it is hot and muggy (St. Louis) and on the backside is is cooler and drier (Kansas City).
You can also tell alot about the weather by observing the wind direction.
Wind is the horizontal movement of air. And the wind direction is the direction from which the wind is blowing, not the direction it is blowing toward.
Southerly winds typically transport warm, moist air while northerly winds are often dry and cooler.
Easterly winds usually mean unsettled weather ahead while westerly winds are often associated with tranquil weather.
But this is all relative on where you live and the topography around you.
It is unusual because this type of storm system is more common in the winter months.
Typically in the south cold fronts and areas of low pressure just don't happen in the summer. About the only hope for precipitaton is from a land-falling tropical system or your every day garden variety pop-up showers and thunderstorms that result from daytime heating and all the abundant moisture in the air.
I think just about every CoCoRaHS station in Alabama and Georgia reported rain on Tuesday.
This area really needed that type of widespread rainfall so I am glad that Mother Nature threw them a curve ball.
Speaking of curve balls, we have one coming down the east side of the Rockies this weekend.
Our highs here in Denver will struggle to reach 70 degrees on Friday and Saturday. Lows should be in the upper 40s and lower 50s.
Our mountains will see a rain/snow mix above the treeline -- which is approximately 11,000 feet.
Fall will be here before you know it -- see make the most of these late summer days.
Today's Lesson
If you love weather, then you want to live in the middle latitudes -- between about 30 and 50° N -- which happens to be where the United States is located.
It is in this region where most of the exciting weather is found as cold air moves down from the Arctic and warm air moves up from the Equator.
Big areas of low pressure (also called middle latitude cyclonic storms) sweep across the country along with a front and make for exciting times.
A front is an area where there is a sharp change in temperature, humidity and wind direction.
Every state in the union can boast an example -- but I think one of the better examples is Missouri -- since there is a major city on each side of the state.
If you were to look at a weather report and Kansas City was 75 degrees with a 38 degree dewpoint, and St. Louis was 90 degrees with a 65 degree dewpoint -- you could easily tell there was a cold front sitting somewhere in between.
On one side it is hot and muggy (St. Louis) and on the backside is is cooler and drier (Kansas City).
You can also tell alot about the weather by observing the wind direction.
Wind is the horizontal movement of air. And the wind direction is the direction from which the wind is blowing, not the direction it is blowing toward.
Southerly winds typically transport warm, moist air while northerly winds are often dry and cooler.
Easterly winds usually mean unsettled weather ahead while westerly winds are often associated with tranquil weather.
But this is all relative on where you live and the topography around you.
Tuesday, August 12, 2008
Weather & Climate
Weather and climate are sometimes used incorrectly in the non-meteorology world.
Think of weather as a current snapshot of conditions at a particular time and place. It is always changing and is comprised of elements such as...
air temperature
air pressure
humidity
clouds
precipitation
visibility
wind
When you measure and observe these weather elements over an interval of time (i.e. years) you obtain the weather average or "climate" for a particular location.
Climate also includes the extremes of weather (i.e. record highs, lows, rainfall, etc.)
Think of weather as a current snapshot of conditions at a particular time and place. It is always changing and is comprised of elements such as...
air temperature
air pressure
humidity
clouds
precipitation
visibility
wind
When you measure and observe these weather elements over an interval of time (i.e. years) you obtain the weather average or "climate" for a particular location.
Climate also includes the extremes of weather (i.e. record highs, lows, rainfall, etc.)
Monday, August 11, 2008
More About The Atmosphere
Up to this point our blog weather lessons have covered the atmosphere in the vertical. We talked about the 4 sections -- troposphere, stratosphere, mesosphere and the thermosphere.
It can also be divided into two sectons based on composition.
The homosphere is from the ground to the lower part of the thermosphere. This lower, well-mixed region of our atmosphere. It is mostly 78% nitrogen and 21% oxygen.
Above that is the heterosphere, where gases seperate. Oxygen and nitrogen tend to settle at the bottom while other lighter weight gases float to the top, such as hydrogen and helium.
You may have heard a term called the ionosphere at some point in your life while taking a science class.
This is not really a layer -- it's just an electrified region within the upper atmosphere where large concentrations of ions and free electrons exist.
The ionosphere plays an important role in radio communications.
OK that's it for the atmosphere -- it is time to get into weather and climate!!!
We'll do that tomorrow!
It can also be divided into two sectons based on composition.
The homosphere is from the ground to the lower part of the thermosphere. This lower, well-mixed region of our atmosphere. It is mostly 78% nitrogen and 21% oxygen.
Above that is the heterosphere, where gases seperate. Oxygen and nitrogen tend to settle at the bottom while other lighter weight gases float to the top, such as hydrogen and helium.
You may have heard a term called the ionosphere at some point in your life while taking a science class.
This is not really a layer -- it's just an electrified region within the upper atmosphere where large concentrations of ions and free electrons exist.
The ionosphere plays an important role in radio communications.
OK that's it for the atmosphere -- it is time to get into weather and climate!!!
We'll do that tomorrow!
Sunday, August 10, 2008
Extreme Weather Magazine Review
Hello everyone, sorry for the lack of blog the past 2 days.
Friday was hectic with work and then I had excitement coming home from work that night. I had to practice TADD.
Does anyone know what that means?
TADD = Turn Around, Don't Drown
We had a thunderstorm pop over east-central Denver Friday evening and it dumped 2-4 inches of rain.
There were some high water rescues along Cherry Creek in downtown and some major traffic issues along I-25 near Alameda.
I live in the SE part of town and on my path home there is a road with a very low spot with signs that say flood water crossing.
After 2.5 years of driving this route and it always being dry, I took my chances.
Sure enough, when I approached the low spot at 11 p.m. water was running rapidly across the road.
I could see all the high water debris marking so I knew it was on the decline, but still, the water was rushing so fast across the road and it was white-capping in the middle -- almost like there was some debris under there.
And wouldn't you know, two STUPID drivers in small sedans tried to go through it and they made it, but I think not much further down the road because they were both pulled over with their flashers on.
I know my "stupid" comment above is a little harsh, but c'mon --- it wasn't that difficult to turn around and go about a mile out of the way to get around it -- ensuring safety of them and potential rescuers.
I have a hybrid SUV that probably would have made it through, BUT I had no idea if the road was still under there as fast as that water was moving.
So anyway, I had heard of the 2-4 inch rain reports and when I got home I ran straight to the backyard to find what had happened over my gauge.
I only had 0.32 inches -- thankfully for the rain but I will admit I was disappointed. I wanted an overflow in my gauge because that is exciting to measure!
So if you want to see the maps of this storm, from the CoCoRaHS page click on maps. Then select Colorado, Denver metro, and 8-9-08.
EXTREME WEATHER MAGAZINE REVIEW
I was recently contacted by a publishing intern from Astronomy magazine. They put together a pilot issue called Extreme Weather -- and depending on the interest level, it could or could not become a regular publication.
It is about 100 pages of full color, short to medium length articles on a variety of weather topics.
This issue has info on chasing storms, lightning, and climate change. It also has information on both new research for the future and past weather, including the Galveston killer hurricane of 1900.
It is chalk full of pictures that are very captivating for the weather guru.
Personally I have enjoyed it, and even a few friends I had over recently managed to find it and read through it. (and they are not weather geeks)
I in particular found an article on page 80 interesting called top 12 weather myths.
So if you want to get a copy of this magazine and express your opinions to the publisher about the potential of making this a regular publication, I invite you to their Web site.
Click here
On the left side there is a section that says Welcome. At the bottom of that article is a link to order.
The magazine is $7.95 in the USA.
Once you get it and look through it, go back to their Web site and let them know what you think. There is a "contact us" link on the top right.
It wouldn't hurt to tell them you heard about this through the CoCoRaHS blog -- I want them to become very familiar with our organization.
There are PLENTY of great weather stories/pictures/experiences that our observers could provide!
Friday was hectic with work and then I had excitement coming home from work that night. I had to practice TADD.
Does anyone know what that means?
TADD = Turn Around, Don't Drown
We had a thunderstorm pop over east-central Denver Friday evening and it dumped 2-4 inches of rain.
There were some high water rescues along Cherry Creek in downtown and some major traffic issues along I-25 near Alameda.
I live in the SE part of town and on my path home there is a road with a very low spot with signs that say flood water crossing.
After 2.5 years of driving this route and it always being dry, I took my chances.
Sure enough, when I approached the low spot at 11 p.m. water was running rapidly across the road.
I could see all the high water debris marking so I knew it was on the decline, but still, the water was rushing so fast across the road and it was white-capping in the middle -- almost like there was some debris under there.
And wouldn't you know, two STUPID drivers in small sedans tried to go through it and they made it, but I think not much further down the road because they were both pulled over with their flashers on.
I know my "stupid" comment above is a little harsh, but c'mon --- it wasn't that difficult to turn around and go about a mile out of the way to get around it -- ensuring safety of them and potential rescuers.
I have a hybrid SUV that probably would have made it through, BUT I had no idea if the road was still under there as fast as that water was moving.
So anyway, I had heard of the 2-4 inch rain reports and when I got home I ran straight to the backyard to find what had happened over my gauge.
I only had 0.32 inches -- thankfully for the rain but I will admit I was disappointed. I wanted an overflow in my gauge because that is exciting to measure!
So if you want to see the maps of this storm, from the CoCoRaHS page click on maps. Then select Colorado, Denver metro, and 8-9-08.
EXTREME WEATHER MAGAZINE REVIEW
I was recently contacted by a publishing intern from Astronomy magazine. They put together a pilot issue called Extreme Weather -- and depending on the interest level, it could or could not become a regular publication.
It is about 100 pages of full color, short to medium length articles on a variety of weather topics.
This issue has info on chasing storms, lightning, and climate change. It also has information on both new research for the future and past weather, including the Galveston killer hurricane of 1900.
It is chalk full of pictures that are very captivating for the weather guru.
Personally I have enjoyed it, and even a few friends I had over recently managed to find it and read through it. (and they are not weather geeks)
I in particular found an article on page 80 interesting called top 12 weather myths.
So if you want to get a copy of this magazine and express your opinions to the publisher about the potential of making this a regular publication, I invite you to their Web site.
Click here
On the left side there is a section that says Welcome. At the bottom of that article is a link to order.
The magazine is $7.95 in the USA.
Once you get it and look through it, go back to their Web site and let them know what you think. There is a "contact us" link on the top right.
It wouldn't hurt to tell them you heard about this through the CoCoRaHS blog -- I want them to become very familiar with our organization.
There are PLENTY of great weather stories/pictures/experiences that our observers could provide!
Thursday, August 7, 2008
Heavy Rain Hits High Plains
It was a wet evening and overnight for much of northeast Colorado, extreme southern Nebraska, and northwest Kansas on Wednesday.
Much needed rain fell but in a few cases it came too fast and caused flooding. Some homes had their basements flooded in and around Greeley, CO.
We even had a few tornado warnings in the northern Denver metro area around 7 pm Wednesday.
I was at my part-time data entry job when the sirens went off in extreme north Denver.
Luckily it was just a few funnel clouds.
The incoming storm system had a lot of energy and dynamics aloft but the vertical wind profile just wasn't really there to create severe storms with tornadoes.
Not that it couldn't have happened --- I just think some people were in the right place at the right time and saw a little action in the clouds last night.
It was very short-lived and the few thunderstorms that developed became absorbed into the more stable, stratiform rain event as we lost daytime heating.
I am going to postpone today's lesson due to a tight schedule today. But stay tuned for tomorrow's blog -- I will post a review for a new national weather magazine I had the chance to review!
Much needed rain fell but in a few cases it came too fast and caused flooding. Some homes had their basements flooded in and around Greeley, CO.
We even had a few tornado warnings in the northern Denver metro area around 7 pm Wednesday.
I was at my part-time data entry job when the sirens went off in extreme north Denver.
Luckily it was just a few funnel clouds.
The incoming storm system had a lot of energy and dynamics aloft but the vertical wind profile just wasn't really there to create severe storms with tornadoes.
Not that it couldn't have happened --- I just think some people were in the right place at the right time and saw a little action in the clouds last night.
It was very short-lived and the few thunderstorms that developed became absorbed into the more stable, stratiform rain event as we lost daytime heating.
I am going to postpone today's lesson due to a tight schedule today. But stay tuned for tomorrow's blog -- I will post a review for a new national weather magazine I had the chance to review!
Wednesday, August 6, 2008
Edouard Could Have Been Worse
T.S. Edouard did little if any damage to Texas and Louisiana. It did bring some moderate to heavy rainfall with a little minor flooding.
The Houston/Galveston area saw 2-5 inches of rainfall with a few 6-7" reports out there. So far this morning the biggest CoCoRaHS report I have seen is 5.03 inches in Jefferson County, TX -- not too far from the towns of Orange and Sabine Pass.
That's a great rainfall -- a bit much, but it can certainly be handled by that part of the world.
Here in the west we would have seen some serious flash flooding and damage from an event like that.
The remnants are compact but are bringing some much needed moisture as it passes through north-central Texas.
The Dallas area awoke to humid but overcast skies with breezy conditions this morning -- a welcome relief from the streak of 100 degree temps.
I was watching The Weather Channel last night before bed and the on-camera meteorologist made an interesting observation.
This HUGE high pressure and bubble of hot dry air that has been parked over the southern plains actually protected Texas and Louisiana from a more serious storm.
The circulation around the high pressure (clockwise) actually steered the storm on a nearly due west-northwest path across the top of the Gulf of Mexico.
But it also fed a lot of that hot, dry air into the storm as well.
This kept Edouard from really ever organizing into something potentially large. Had that hot, dry air not been in place, the warm waters could have easily allowed Edouard to rapidly increase in size and strength.
TODAY's LESSON
So yesterday we talked about the layers of the atmoshpere and I said we live in the lowest layer, called the troposphere, which is approx. 7 miles above the surface.
And although the overall temperature trend is to decrease with height, you will find small layers where pockets of warmer temperatures can be found and this helps to drives our weather.
The rate of cooling as you go up is called the lapse rate.
As you picture the atmosphere, you have to think vertically, or 3-D, so mentally picture anything that helps. (i.e. stacking blocks)
Once you reach the top of the troposphere, the lapse rate becomes zero, meaning the temperature stops decreasing with height and becomes constant with height.
This region is called an isothermal (or an equal temperature zone). The bottom of this new layer marks the end of the troposphere and the beginning of the second layer in our atmosphere, which is called the stratosphere.
The boundary that seperates the two layers is called the tropopause.
The tropopause, or trop (with a long O sound) in weatherman lingo, is important to meteorologists because it's height varies with both season and location.
It also helps identify the jet stream, which is the fast river of air current that circles the globe and drives weather patterns.
So now that we are into the stratosphere,the beginning of it marks a layer with constant temperature as you increase in height, between about 7-12 miles above the surface.
Then the temperature begins to warm with height, which is called a temperature inversion. The inversion is deep, meaning the layer where temperature warms is several miles up.
This does a few things...it acts like a giant cap and keeps the troposphere locked in about the lowest 7 miles. It prevents stratospheric air from mixing down into the troposphere (obviously there could be a little mixing where the two layers meet at the tropopause, but it isn't significant).
Now even though the temperature is warming with height in most of the stratosphere, it is still extremely cold, averaging less than -46°C.
The layer of warmer air in the stratosphere is due to the gas ozone retaining heat.
At the top of the stratosphere, you will find the stratopause, which is the boundary between the 3rd layer of atmosphere called the mesosphere (middle sphere).
Air at this level is VERY thin and pressure is quite low, averaging about 1 mb. (compared to 1013.25 mb at sea level)
Nitrogen and oxygen levels here are about the same as found at sea level, but you couldn't survive long breathing without proper equipment. The brain would experience hypoxia, meaning it would become oxygen starved.
There is little ozone in this layer so after a small transition of air temperature remaining constant with height, the temperature once again starts to decrease with height.
In the mesosphere, Earth's atmosphere reaches it lowest overall average value of -90°C.
At the top of the mesosphere is the mesopause, marking the transition to the 4th and highest layer of our atmosphere, the thermosphere.
As it transitions the temperature goes back to constant with height then starts to increase with height until reaching space.
The mesosphere is known as the hot layer. Here the oxygen molecules absorb solar energy. Temperatures actually vary from day to day depending on solar activity.
The air here is actually too thin to measure temperature with a thermometer, but it can be determined by observing the orbital change of satellites caused by the drag of our atmosphere.
At the very top of the mesosphere you will have reached the top of our atmosphere, an area where molecules shoot off into space. This region is sometimes called the exosphere. (exiting the atmosphere)
WOW! We got through all the layers of the atmosphere.
Below is a link to a website with a little more information AND a graph that shows the temperature profile from the ground to the top, putting all this information together visually for you.
Web site for Temp. Profle of Earth's Atmosphere
The Houston/Galveston area saw 2-5 inches of rainfall with a few 6-7" reports out there. So far this morning the biggest CoCoRaHS report I have seen is 5.03 inches in Jefferson County, TX -- not too far from the towns of Orange and Sabine Pass.
That's a great rainfall -- a bit much, but it can certainly be handled by that part of the world.
Here in the west we would have seen some serious flash flooding and damage from an event like that.
The remnants are compact but are bringing some much needed moisture as it passes through north-central Texas.
The Dallas area awoke to humid but overcast skies with breezy conditions this morning -- a welcome relief from the streak of 100 degree temps.
I was watching The Weather Channel last night before bed and the on-camera meteorologist made an interesting observation.
This HUGE high pressure and bubble of hot dry air that has been parked over the southern plains actually protected Texas and Louisiana from a more serious storm.
The circulation around the high pressure (clockwise) actually steered the storm on a nearly due west-northwest path across the top of the Gulf of Mexico.
But it also fed a lot of that hot, dry air into the storm as well.
This kept Edouard from really ever organizing into something potentially large. Had that hot, dry air not been in place, the warm waters could have easily allowed Edouard to rapidly increase in size and strength.
TODAY's LESSON
So yesterday we talked about the layers of the atmoshpere and I said we live in the lowest layer, called the troposphere, which is approx. 7 miles above the surface.
And although the overall temperature trend is to decrease with height, you will find small layers where pockets of warmer temperatures can be found and this helps to drives our weather.
The rate of cooling as you go up is called the lapse rate.
As you picture the atmosphere, you have to think vertically, or 3-D, so mentally picture anything that helps. (i.e. stacking blocks)
Once you reach the top of the troposphere, the lapse rate becomes zero, meaning the temperature stops decreasing with height and becomes constant with height.
This region is called an isothermal (or an equal temperature zone). The bottom of this new layer marks the end of the troposphere and the beginning of the second layer in our atmosphere, which is called the stratosphere.
The boundary that seperates the two layers is called the tropopause.
The tropopause, or trop (with a long O sound) in weatherman lingo, is important to meteorologists because it's height varies with both season and location.
It also helps identify the jet stream, which is the fast river of air current that circles the globe and drives weather patterns.
So now that we are into the stratosphere,the beginning of it marks a layer with constant temperature as you increase in height, between about 7-12 miles above the surface.
Then the temperature begins to warm with height, which is called a temperature inversion. The inversion is deep, meaning the layer where temperature warms is several miles up.
This does a few things...it acts like a giant cap and keeps the troposphere locked in about the lowest 7 miles. It prevents stratospheric air from mixing down into the troposphere (obviously there could be a little mixing where the two layers meet at the tropopause, but it isn't significant).
Now even though the temperature is warming with height in most of the stratosphere, it is still extremely cold, averaging less than -46°C.
The layer of warmer air in the stratosphere is due to the gas ozone retaining heat.
At the top of the stratosphere, you will find the stratopause, which is the boundary between the 3rd layer of atmosphere called the mesosphere (middle sphere).
Air at this level is VERY thin and pressure is quite low, averaging about 1 mb. (compared to 1013.25 mb at sea level)
Nitrogen and oxygen levels here are about the same as found at sea level, but you couldn't survive long breathing without proper equipment. The brain would experience hypoxia, meaning it would become oxygen starved.
There is little ozone in this layer so after a small transition of air temperature remaining constant with height, the temperature once again starts to decrease with height.
In the mesosphere, Earth's atmosphere reaches it lowest overall average value of -90°C.
At the top of the mesosphere is the mesopause, marking the transition to the 4th and highest layer of our atmosphere, the thermosphere.
As it transitions the temperature goes back to constant with height then starts to increase with height until reaching space.
The mesosphere is known as the hot layer. Here the oxygen molecules absorb solar energy. Temperatures actually vary from day to day depending on solar activity.
The air here is actually too thin to measure temperature with a thermometer, but it can be determined by observing the orbital change of satellites caused by the drag of our atmosphere.
At the very top of the mesosphere you will have reached the top of our atmosphere, an area where molecules shoot off into space. This region is sometimes called the exosphere. (exiting the atmosphere)
WOW! We got through all the layers of the atmosphere.
Below is a link to a website with a little more information AND a graph that shows the temperature profile from the ground to the top, putting all this information together visually for you.
Web site for Temp. Profle of Earth's Atmosphere
Tuesday, August 5, 2008
Rain, Heat, Storms -- We've Got It All
Wow, was it ever wet in the Chicago-land area on Monday. Much of the region saw a widespread 1-3 inches of rainfall.
It was double that across northwest Indiana -- with 3 to 7 inches of rain falling across a 5-county area.
As I write this morning's blog heavy rain is falling across central and portions of southern Indiana, thanks to a MCS -- mesoscale convective system.
Now that is a weather term you can drop at your next dinner party and impress the socks off those you know.
The MCS is a complex of thunderstorms that become organized on a larger scale than just an individual thunderstorm. It normally persists for several hours and they usually form in the evening hours.
It must meet a certain size criteria -- which is about 60 miles in at least one direction.
As they persist into the overnight they often turn into MCC's, a mesoscale convective complex.
These are typically nocturnal (meaning overnight) and are associated with lots of rain and lightning, but wind is common too. MCC's usually have a large, circular cloud shield as viewed from a satellite.
Tropical Storm Edouard has arrived in coastal Texas. It will bring heavy rain and wind to much of Texas over the next few days.
We should see a really nice footprint on tomorrow's CoCoRaHS maps of the landfall in Texas, as well as in adjacent areas of southwest Louisiana.
TODAY'S LESSON
So yesterday I teased you saying that we know both air pressure and air density decrease with height, but does temperature always cool with height?
Air temperature normally decreases from the surface of the Earth up to about 7 miles, or 36,000 feet.
This is due to the fact that sunlight warms the ground, and the ground in turn warms the air immediately above it.
The rate at which the air temperature decreases with height is called the lapse rate, and the standard (or average) lapse rate in this region of the lower atmosphere (the bottom 7 miles or so) is about 3.6°F for every 1,000 feet you rise in elevation.
Now you see why us Denverites go to the high country to play on the hot summer days in the city.
The above figures are only averages. There are definitely days when the air becomes colder more quickly as you move upward. This would "steepen" the lapse rate.
Some days the air cools more slowly with height, and the lapse rate would be less than the standard of 3.6°F.
And still yet, there are some days when the air warms with height, producing a condition known as a temperature inversion.
The region of the atmosphere (from the surface up to about 7 miles) contains all the weather we are familiar with on Earth.
It is kept well mixed by rising and sinking air currents -- and is called the troposphere.
Each day, hundreds of weather balloons are released around the world that carry a radiosonde.
The radiosonde measures important weather variables as it rises 100,000 feet into the air.
One of those variables is temperature -- and the data it sends back gives us a temperature profile of the atmosphere.
Although the overall trend in the troposphere is that temperature cools with height, there can be layers where the air is warmer than that above or below it.
This is part of the dynamic that drives our weather, and is very important when forecasting. A meteorologist always looks at the temperature profile of the atmosphere because at some point that air is going to mix out (thanks to air currents) and it could have an impact on what kind of weather we see at the surface.
Probably the best example I can give you that most have heard at some point in their life from their favorite local t.v. meteorologist is the "cap" in the atmosphere.
This is a layer of warm air aloft that acts like a block for cloud and thuderstorm development. However, as conditions change in the environment of the upper atmosphere and cloud growth can punch through the layer of warm air (this is called breaking the cap) --- things change rapidly and thuderstorms can grow rapidly.
The troposphere is just one layer of the atmosphere -- where we live and where the weather occurs.
Tomorrow we will explore the other 3 layers.
It was double that across northwest Indiana -- with 3 to 7 inches of rain falling across a 5-county area.
As I write this morning's blog heavy rain is falling across central and portions of southern Indiana, thanks to a MCS -- mesoscale convective system.
Now that is a weather term you can drop at your next dinner party and impress the socks off those you know.
The MCS is a complex of thunderstorms that become organized on a larger scale than just an individual thunderstorm. It normally persists for several hours and they usually form in the evening hours.
It must meet a certain size criteria -- which is about 60 miles in at least one direction.
As they persist into the overnight they often turn into MCC's, a mesoscale convective complex.
These are typically nocturnal (meaning overnight) and are associated with lots of rain and lightning, but wind is common too. MCC's usually have a large, circular cloud shield as viewed from a satellite.
Tropical Storm Edouard has arrived in coastal Texas. It will bring heavy rain and wind to much of Texas over the next few days.
We should see a really nice footprint on tomorrow's CoCoRaHS maps of the landfall in Texas, as well as in adjacent areas of southwest Louisiana.
TODAY'S LESSON
So yesterday I teased you saying that we know both air pressure and air density decrease with height, but does temperature always cool with height?
Air temperature normally decreases from the surface of the Earth up to about 7 miles, or 36,000 feet.
This is due to the fact that sunlight warms the ground, and the ground in turn warms the air immediately above it.
The rate at which the air temperature decreases with height is called the lapse rate, and the standard (or average) lapse rate in this region of the lower atmosphere (the bottom 7 miles or so) is about 3.6°F for every 1,000 feet you rise in elevation.
Now you see why us Denverites go to the high country to play on the hot summer days in the city.
The above figures are only averages. There are definitely days when the air becomes colder more quickly as you move upward. This would "steepen" the lapse rate.
Some days the air cools more slowly with height, and the lapse rate would be less than the standard of 3.6°F.
And still yet, there are some days when the air warms with height, producing a condition known as a temperature inversion.
The region of the atmosphere (from the surface up to about 7 miles) contains all the weather we are familiar with on Earth.
It is kept well mixed by rising and sinking air currents -- and is called the troposphere.
Each day, hundreds of weather balloons are released around the world that carry a radiosonde.
The radiosonde measures important weather variables as it rises 100,000 feet into the air.
One of those variables is temperature -- and the data it sends back gives us a temperature profile of the atmosphere.
Although the overall trend in the troposphere is that temperature cools with height, there can be layers where the air is warmer than that above or below it.
This is part of the dynamic that drives our weather, and is very important when forecasting. A meteorologist always looks at the temperature profile of the atmosphere because at some point that air is going to mix out (thanks to air currents) and it could have an impact on what kind of weather we see at the surface.
Probably the best example I can give you that most have heard at some point in their life from their favorite local t.v. meteorologist is the "cap" in the atmosphere.
This is a layer of warm air aloft that acts like a block for cloud and thuderstorm development. However, as conditions change in the environment of the upper atmosphere and cloud growth can punch through the layer of warm air (this is called breaking the cap) --- things change rapidly and thuderstorms can grow rapidly.
The troposphere is just one layer of the atmosphere -- where we live and where the weather occurs.
Tomorrow we will explore the other 3 layers.
Monday, August 4, 2008
Much To Talk About
It will be a busy week for weather headlines with Tropical Storm Edouard topping them most likely.
This system developed over the weekend out of a cluster of unsettled weather over the northeast Gulf of Mexico.
The storm is moving west and should make landfall near Houston, TX by Wednesday.
It could pull a "Dolly" and strengthen into a hurricane before landfall.
Either way, it will be a wet and stormy time for residents along the upper Texas coast and in portions of coastal Louisiana.
Meanwhile, the bubble of extreme heat will shift east this week. Here in Denver we will finall break our 90° streak on Tuesday if the forecast holds. That would make the new record streak of 90 degrees or higher stand at 23 days.
Recall we broke the previous streak of 18 days last week. That record was originally set in 1874 and tied again in 1901.
The streak of 100s will continue for Dallas, TX and more record highs are possible today over the plains states.
Here are some record highs from Sunday around the country...
107° Dallas/Ft. Worth Airport, TX (previous 105° in 1998)
106° Oklahoma City, OK (tied - previously in 1930)
105° McAlester, OK (previous 103° set in 1956)
104° N. Little Rock, AR (previous 103° set in 1987)
103° Pueblo, CO (tied - previously in 1902)
Today's Lesson
Billions of air molecules push on the human body. This force is exerted equally in all directions.
At the same time, billions of molecules on the inside of the body push outward just as hard -- which balances the force.
We don't directly feel these "pushing" forces of the air, but we can detect changes in air pressure quickly. (i.e. ears popping when we rapidly change elevation)
Air molecules both take up space and have weight. In fact air is heavy -- with the weight of all the air around the Earth coming in at a staggering 5600 trillion tons.
This weight acts as a force upon the Earth.
The amount of force exerted over an area of surface is called atmospheric pressure, or simply, air pressure.
As you climb in elevation from sea level, the air pressure decreases -- rapidly at first through the first 10 miles, then more slowly.
So if you have ever been here in Colorado, and visited any of our 54 mountain peaks that top 14,000 feet -- you have been above nearly half of all the molecules in the atmosphere.
The summit of Mt. Everest is above nearly 70% of all the molecules in the atmosphere. (approx. 29,000 feet)
So far, through our daily blog lessons, you have learned that both air pressure and air density decreases with height above the Earth's surface.
Temperature is a different story, however. It has a much more complicated vertical profile.
We are often led to believe that it cools with height overall, bit is that really so?
Tune in tomorrow and we'll find out!
This system developed over the weekend out of a cluster of unsettled weather over the northeast Gulf of Mexico.
The storm is moving west and should make landfall near Houston, TX by Wednesday.
It could pull a "Dolly" and strengthen into a hurricane before landfall.
Either way, it will be a wet and stormy time for residents along the upper Texas coast and in portions of coastal Louisiana.
Meanwhile, the bubble of extreme heat will shift east this week. Here in Denver we will finall break our 90° streak on Tuesday if the forecast holds. That would make the new record streak of 90 degrees or higher stand at 23 days.
Recall we broke the previous streak of 18 days last week. That record was originally set in 1874 and tied again in 1901.
The streak of 100s will continue for Dallas, TX and more record highs are possible today over the plains states.
Here are some record highs from Sunday around the country...
107° Dallas/Ft. Worth Airport, TX (previous 105° in 1998)
106° Oklahoma City, OK (tied - previously in 1930)
105° McAlester, OK (previous 103° set in 1956)
104° N. Little Rock, AR (previous 103° set in 1987)
103° Pueblo, CO (tied - previously in 1902)
Today's Lesson
Billions of air molecules push on the human body. This force is exerted equally in all directions.
At the same time, billions of molecules on the inside of the body push outward just as hard -- which balances the force.
We don't directly feel these "pushing" forces of the air, but we can detect changes in air pressure quickly. (i.e. ears popping when we rapidly change elevation)
Air molecules both take up space and have weight. In fact air is heavy -- with the weight of all the air around the Earth coming in at a staggering 5600 trillion tons.
This weight acts as a force upon the Earth.
The amount of force exerted over an area of surface is called atmospheric pressure, or simply, air pressure.
As you climb in elevation from sea level, the air pressure decreases -- rapidly at first through the first 10 miles, then more slowly.
So if you have ever been here in Colorado, and visited any of our 54 mountain peaks that top 14,000 feet -- you have been above nearly half of all the molecules in the atmosphere.
The summit of Mt. Everest is above nearly 70% of all the molecules in the atmosphere. (approx. 29,000 feet)
So far, through our daily blog lessons, you have learned that both air pressure and air density decreases with height above the Earth's surface.
Temperature is a different story, however. It has a much more complicated vertical profile.
We are often led to believe that it cools with height overall, bit is that really so?
Tune in tomorrow and we'll find out!
Saturday, August 2, 2008
Hot & Dry Weekend
It was a hot and dry start to the weekend with widespread 90s and 100s from the Rocky Mountains to the deep south.
Denver set a new record high of 104 degrees on Friday. Wichita Falls, TX tied their record high of 108 degrees. North Little Rock, AR (where I was born) tied their record high of 103 degrees.
I am writing this blog at 3pm on Saturday and we have set another record here in Denver at 102 degrees today.
But get this....we had a heat index of 95 when it was 102 degrees. The dewpoint was 27 and the relative humidity was 7%.
Jacksonville, AR (just down the road from N. Little Rock) was 102 degrees with a heat index of 113 degrees. The dewpoint was 73 degrees with a relative humidity of 40%.
I am SO glad I am not back home today.
The hot air is spreading east and north over the next few days, so places like Chicago and Minneapolis can expect a warm up.
Today's Lesson
We're ready to talk about density of the air. This is determined by the masses of all atoms and molecules and the amount of space between them.
In other words, density tells us how much matter is in a given space. (that is volume)
Mathematically, it looks like this.
Density = (mass ÷ volume)
There are considerably more molecules within the same size volume of air near the Earth's surface than at higher levels.
Air density decreases with height, rapidly at first, then more slowly the higher you go in the atmosphere.
Air molecules are always in motion. They bounce around off people, objects, even your plants and trees.
Each time an air molecule hits something, it gives a tiny push.
This small force (push) divided by the area on which it pushes is called pressure.
Pressure = (force ÷ area)
I bet by now you are thinking so how in the heck do you measure air?
Well luckily there is a standard to go by.
If you took a column of air (1 square inch in size) that extended from the ocean surface to the top of the atmosphere, it would weigh about 14.7 pounds.
Therefore, normal atmospheric air pressure near sea level is close to 14.7 pounds per square inch.
If more molecules were packed into that column, it'd become more dense or heavier, and since the air would weigh more pressure would go up. (high pressure)
The opposite would be low pressure if there were fewer molecules of air in that 1 square inch column.
Now in weather we don't typically measure air pressure in pounds per square inch. The most common unit used to measure air pressure is the millibar.
The hectopascal (hPa) is also widely used in science as is mercury (Hg) on television and in weather reports that go out to the public.
Here are the conversions for standard sea level pressure. All 4 of the following are equal.
14.7 pounds per square inch is standard sea level pressure
which converts to 1013.25 mb
or 1013.25 hPa
or 29.92 in. Hg
Tomorrow we'll dive a little deeper into air pressure.
Denver set a new record high of 104 degrees on Friday. Wichita Falls, TX tied their record high of 108 degrees. North Little Rock, AR (where I was born) tied their record high of 103 degrees.
I am writing this blog at 3pm on Saturday and we have set another record here in Denver at 102 degrees today.
But get this....we had a heat index of 95 when it was 102 degrees. The dewpoint was 27 and the relative humidity was 7%.
Jacksonville, AR (just down the road from N. Little Rock) was 102 degrees with a heat index of 113 degrees. The dewpoint was 73 degrees with a relative humidity of 40%.
I am SO glad I am not back home today.
The hot air is spreading east and north over the next few days, so places like Chicago and Minneapolis can expect a warm up.
Today's Lesson
We're ready to talk about density of the air. This is determined by the masses of all atoms and molecules and the amount of space between them.
In other words, density tells us how much matter is in a given space. (that is volume)
Mathematically, it looks like this.
Density = (mass ÷ volume)
There are considerably more molecules within the same size volume of air near the Earth's surface than at higher levels.
Air density decreases with height, rapidly at first, then more slowly the higher you go in the atmosphere.
Air molecules are always in motion. They bounce around off people, objects, even your plants and trees.
Each time an air molecule hits something, it gives a tiny push.
This small force (push) divided by the area on which it pushes is called pressure.
Pressure = (force ÷ area)
I bet by now you are thinking so how in the heck do you measure air?
Well luckily there is a standard to go by.
If you took a column of air (1 square inch in size) that extended from the ocean surface to the top of the atmosphere, it would weigh about 14.7 pounds.
Therefore, normal atmospheric air pressure near sea level is close to 14.7 pounds per square inch.
If more molecules were packed into that column, it'd become more dense or heavier, and since the air would weigh more pressure would go up. (high pressure)
The opposite would be low pressure if there were fewer molecules of air in that 1 square inch column.
Now in weather we don't typically measure air pressure in pounds per square inch. The most common unit used to measure air pressure is the millibar.
The hectopascal (hPa) is also widely used in science as is mercury (Hg) on television and in weather reports that go out to the public.
Here are the conversions for standard sea level pressure. All 4 of the following are equal.
14.7 pounds per square inch is standard sea level pressure
which converts to 1013.25 mb
or 1013.25 hPa
or 29.92 in. Hg
Tomorrow we'll dive a little deeper into air pressure.
Friday, August 1, 2008
Whew, It's H-H-HOT!
Much of the country is sweltering today with extreme heat.
There are heat advisories posted for portions of Colorado, Texas, Oklahoma, Arkansas, Tennessee, Kansas and Missouri.
Red flag warnings for extreme high fire danger cover many locations in the Rockies.
Denver broke it's longest streak of 90-degree days with yesterday being day 19. The previous all-time record streak was 18 days.
We are expected to be in the upper 90s and low 100s through early next week so this is quite remarkable.
In fact, today we should hit or beat 100° and that would tie or break the day's record high of 100°.
We are lucky that we live in a dry climate and although it does get hot, we quickly fall back into the 70s not too longer after sunset.
I have to cancel today's weather lesson as I am running late for work. I will make up for it over the weekend.
By the way, observer GA-FT-11 reported 5.69" of rain on Thursday. That is really something seeing as how dry this part of the world has been in recent months.
I checked his/her reports but found no comment. If you happen to see this blog, can you tell us more about that rainfall? If you weren't home, did you see signs of the heavy rain when you got home, i.e. flower beds washed out, etc?
Just curious....didn't mean to put you on the spot in my blog! ;-)
If we had a rain like that here in Colorado it would have been on national news and potentially life threatening.
Our annual precipitaton in Denver is just a little over 15" a year!
Stay safe everyone and keep cool!!!
There are heat advisories posted for portions of Colorado, Texas, Oklahoma, Arkansas, Tennessee, Kansas and Missouri.
Red flag warnings for extreme high fire danger cover many locations in the Rockies.
Denver broke it's longest streak of 90-degree days with yesterday being day 19. The previous all-time record streak was 18 days.
We are expected to be in the upper 90s and low 100s through early next week so this is quite remarkable.
In fact, today we should hit or beat 100° and that would tie or break the day's record high of 100°.
We are lucky that we live in a dry climate and although it does get hot, we quickly fall back into the 70s not too longer after sunset.
I have to cancel today's weather lesson as I am running late for work. I will make up for it over the weekend.
By the way, observer GA-FT-11 reported 5.69" of rain on Thursday. That is really something seeing as how dry this part of the world has been in recent months.
I checked his/her reports but found no comment. If you happen to see this blog, can you tell us more about that rainfall? If you weren't home, did you see signs of the heavy rain when you got home, i.e. flower beds washed out, etc?
Just curious....didn't mean to put you on the spot in my blog! ;-)
If we had a rain like that here in Colorado it would have been on national news and potentially life threatening.
Our annual precipitaton in Denver is just a little over 15" a year!
Stay safe everyone and keep cool!!!
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