What is the significance of air pressure when the news displays the weather?

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Every night at the end of the News the weatherman comes on and tells us the weather.

The obvious things that matter to Average Joe is the minimum and maximum temperatures as well as the general weather pattern (sunny, windy, rainy, etc) but they always go on about “low pressure systems”.

I’ve got a flight simulator and understand that the altimeter needs to be calibrated to the correct pressure but don’t really understand what that means outside of making sure the altimeter displays the correct altitude, and also I’ve got no idea why anyone who isn’t a pilot cares about the air pressure, or why it’s on the News.

In: Planetary Science

3 Answers

Anonymous 0 Comments

The air pressure tells you why you get those specific temperatures and weather patterns. Air moves from high pressure to low pressure. Due to the rotation of the Earth it moves clockwise around the high pressure system and anti-clockwise around the low pressure system in the northern hemisphere, opposite in the southern. So if you see a pressure map you should be able to see how the winds spiral out from the high pressure areas and spiral inwards towards the low pressure areas. So now you know the prevailing winds. You can then see if the winds come from a place where it is usually cold or a place where it is usually warm and now you know the general temperature. Similarly you can see if the winds come from an ocean or land which tells you the general humidity. So now you can tell how likely it is to form clouds or even rain.

This is something that pilots in particular have to learn. Things such as the prevailing winds are very important to pilots but not often reported on weather maps for the general public. Not just because you would want to fly with the winds but it can help you identify areas of turbulence. You also get a much better understanding of the weather when you see it change throughout the day. A weather forecast is usually made just a few times a day and is usually behind the measurements by a few hours. But if you know how the winds are on a particular day and understand the weather you can react to changes in real time. For example if a city a hundred miles away reports that it started raining when no rain was forecasted you can tell the forecast was wrong about the humidity or maybe the high pressure system moved a bit differently and you can quickly estimate how that is going to impact the weather in the area you are in.

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