Under Pressure!

Image Courtesy of NOAA
Written by: Scott Hetsko

Everyday in our weather casts on News 8, we blab on and on about high or low pressure and how it affects you! This is all relative in the atmosphere. Air pressure is simply the weight of the air above you. The atoms and molecules that make up the various layers in the atmosphere are always moving in random directions. Despite their tiny size, when they strike a surface they exert pressure.
Each molecule is too small to feel and only exerts a tiny bit of pressure. However, when we add up the all the pressures from the large number of molecules that strike a surface each moment, then the total pressure is considerable. This is air pressure. As the density of the air increases, then the number of strikes per unit of time and area also increases. As you go up in height, there is less air (less dense) so the air pressure decreases. Click on the picture to the right to see how quickly pressure falls!