From the Ask Todd section on WBIR.com, a fan asked "Todd, what does 'pressure' really mean?"
Air pressure is the force exerted on you by the weight of tiny air particles, also known as air molecules.
Although those molecules are invisible, they still have weight, and they still take up space, and since there's a lot of "empty" space between air molecules, air can be compressed to fit in a smaller volume.
Weather forecasters measure air pressure with a barometer.
Here's two good rules of thumb that can help you know what kind of weather to expect:
- If a high pressure system is on its way, often you can expect clear skies and typically cooler temperatures.
- If a low pressure system is coming, then look for clouds and rain and typically milder temperatures.