The weather in the Midwest has been wild this summer. There have been many reports of tornado damage and severe flooding across several states in the region. Why does wild weather happen during this time of year?

It’s all about Heat

It is common knowledge that temperatures rise as winter changes into spring and summer. Higher temperatures means more heat, and heat is the driving force behind wild weather. This is why you don’t see thunderstorms in the winter.

Wild weather occurs when the air is warm, full of moisture, and unstable. It is easy to figure out when the air is warm and full of moisture, just think of a hot and humid day. How can you tell if the air is unstable?

Use your eyes

The air above us can either be stable or unstable. The easiest way to tell if the air is unstable is to look at the clouds in the sky. Tall and puffy clouds are a sure sign of unstable air. If the air is stable, the clouds will form a flat layer.

Here is a picture I took of a tall and puffy Thunderstorm cloud (called a Cumulonimbus) while flying over Florida. This cloud was able to get very tall and puffy because the air is very unstable.

Meteorologist (weather scientists) know when wild weather is coming by study charts and data from satellites in space. 

Take a look at this weather map from the National Oceanic and Atomspheric Adminstration (NOAA). What do you notice?

The “H” and “L” you see on the map refers to areas of High pressure and Low pressure. The weather person on TV will refer to this as “barometric pressure” and will say if it is rising or falling.

In general:

– If the barometric pressure is rising or is High, expect good weather.

– If the barometric pressure is falling or is Low, expect bad weather.

Notice that the areas of low pressure have a lot of rain and thunderstorm warnings.

Another thing to notice are the lines of blue flags and red half circles. These lines indicate a weather front. What is a weather front? 

A weather front is the boundary between two different air masses. Cold fronts are the line of blue flags and warm fronts are the line of red half circles. The direction that the flags and circles are pointing show the way the weather fronts are moving.

As a general rule, when opposite weather fronts (warm and cold) collide, wild weather will happen. Notice that there is an area shaded in yellow that warns “Severe Thunderstorms Possible” near where a warm front is cutting a cold front in half.

The Big Picture

The weather map shown above is a typical example of what happens during the summer over the middle of America. Cold dry air from the Artic moves south over Canada, while warm moist air from the Gulf of Mexico moves north. These air masses collide and cause wild summer weather. Sometimes the storms can be so big that is stretches across the U.S. from north to south.

These storms can pack a punch, which means it has energy in the form of heat and wind. I wonder if scientists can create a technology that drains a storm of this energy and transform it into electricity. This way, the storm won’t cause damage and people will have a natural source of power. What do you think?

Dr. Dave