(Courtesy of NOAA)

High-pressure systems linger over the Southwest creating hot weather.

This week has been the hottest so far in 2014. Weather forecasters talk about the heat and high-pressure systems. But what exactly are they?

The short answer: it makes you sweat. ASU Meteorology Professor Randy Cerveny gives us the long answer. He said high-pressure systems can cover the entire Southwest and last for weeks.

“These big H’s that you see on the weather map are areas where the air is basically sinking. As air sinks it gets compressed. It’s like pushing a tire pump, as you’re pushing down. You’re pushing that air tighter and tighter and the pump would actually get hotter,” said Cerveny. 

Cerveny said as the air is pushed down towards the surface it heats up. These systems either need to be broken up by moisture or moved by the jet stream. And the systems expand during the summer because of the Earth’s position in relation to the sun.