Thursday, July 31, 2008

Dogs Days of Summer

The "dog days of summer" are upon us. This refers to the hottest, most sultry days of the year, typically starting in mid to late July and lasting through most of August.

The period is best described as hot and stagnant with little progress or change in the weather patterns.

The term "dog days" was used by the Greeks and Romans as they tracked Sirius (the Dog Star). It was popularly believed to be an evil time when the seas boiled, wine turned sour, dogs grew mad and man became sick with fever and hysterics.

The "dog days" originally were the days when Sirius rose just before or at the same time as the sun.

For ancient Egyptians, the star Sirius appeared just before the season when the Nile River flooded. The this also was the time the weather turned hot and sultry. It prompted the saying, "Dog Days bright and clear, indicate a happy year. But when accompanied by rain, for better times our hopes are vain."

"Dog Days" are also associated with the US Stock market, since in the summer stocks tend to be slow and poorly performing stocks with little future potential are called dogs.

And in hot, humid climates, the dog days are associated with "dogging" around, or being "dog tired."

Today's Lesson

If you were to go out and start a meteorology degree, chances are you will have to get a minor in math, or at least take several classes in the field.

Meteorology coursework involves a lot of work with equations.

We'll do a little basic math in today's topic.

Although the atmoshere extends several miles above the Earth, most of it can be found closest to the surface.

This is because of gravity, pulling down on the air above, and squeezing (or compressing) air molecules closer together.

The more air above a certain level, the greater the squeezing force.

Gravity also has an effect on the weight of objects, including air. In fact, weight is the force upon an object due to gravity.

Mathematically, weight = mass X gravity.

Here is an example. Say you have a container of air, it'd weigh the same anywhere you travel on Earth. But if you instantly went to the moon, where the force of gravity is 1/6 of what it is here on Earth, that same container of air would weigh 1/6 less on the moon.

Now let's talk about two different measurements, mass and volume.

Mass is the weight of an object, and is measured in grams or kilograms typically.

A volume is telling you how much matter is in a given space. Since it is a space, volume is expressed in cubic measurements. (usually cubic centimeters or meters)

I know that is a lot to take in -- esp. if you are one that tends to get lost with any type of math talk.

I had to introduce that before we dive into density and pressure, two things you really have to grasp to understand weather.

We'll get into that tomorrow.

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