High and low-pressure systems basically even out the unequal heating from the sun. They influence common weather patterns that your News4JAX meteorologists talk about all the time.
As meteorologists, we know the ins and outs of the “highs” and “lows” of weather on Earth, thanks to changes in atmospheric pressure.
But have you ever been curious as to why we’re so infatuated with all those blue H’s and red L’s on a weather map?
Differences in air pressure are a crucial part of the changing weather conditions on the planet. The sun’s uneven heating of the Earth’s surface emanates temperature differences, essentially where the warm tropics mix with the cold polar regions bringing about pressure changes.
Think of it like this — as tropical air rises, it brings about lower pressure at the surface (think of it as “missing” some air that just rose off the surface, meaning the pressure has dropped), while cold, sinking air can create areas of high pressure.
As the air rises inside lower pressure, it will cool and condense into clouds and eventually become rain and/or snow (Obviously rain is the common weather-maker for those of us here in Florida).
Also worth noting is that because of the Earth’s rotation and the Coriolis Effect — winds inside a low-pressure center will always spin counterclockwise in the Northern Hemisphere (and reverse in the Southern Hemisphere).
Intense lows can create very serious thunderstorms with strong winds and heavy rain. Lows are also known as “troughs” due to the dips in pressure lines which you will notice when we draw it on our weather maps.
Now, let’s tackle high-pressure systems! High pressure involves sinking air. The sinking air dries and warms, leaving areas under high pressure. With a high-pressure system, we almost always have clear skies and calm winds in the forecast.
As air flows away from the high, the wind spins clockwise in the Northern Hemisphere and the reverse in the Southern Hemisphere.
Intense high-pressure systems can create heatwaves, drought during the summer months, and arctic conditions in the winter months for different parts of the country. For us in Florida, we experience drier conditions and cooler conditions.
High-pressure systems are drawn on weather maps in a line with ridges. They move in, and they move out and that’s why the weather patterns change so often.
There are various types of high-pressure systems known as “The Bermuda High,” “The Four Corners High,” “Arctic Highs,” and “The North Pacific High.”
Low-pressure systems have various names too, such as the “Aleutian Low”, “Nor’ Easter”, “the “Colorado Low”, the “Alberta Clipper”, the “Cutoff Low”, and the “Lee-Side Low.”
If you ever have questions about what these very specific systems do, email any of our meteorologists! We are here to answer your questions!
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