What does the 'H' on a weather map actually mean? | Weather | ABC Australia

What does the 'H' on a weather map actually mean? #ABCWeather #Weather #LearnOnYouTube #WeatherMap

You might think the Big H and L on a weather map stand for high and low temperature, right? Wrong.

It’s actually talking about air pressure. Let’s start with high pressure.

When air is heated by sunlight it rises higher into the atmosphere, but when it gets up there, it cools down.

That cold air is now denser than the air below it, so it wants to push down and spread out.

You might think this would cool things down, but as the air sinks back to the surface, it heats up.

Warm, dry air means no clouds, and with no clouds there’s nothing to soak up light and heat coming from the sun, so when you see the H near you on the map, it often means higher temperatures, less rain and light wind.

At this time of the year, you’ll frequently see a High hanging around the Great Australian Bight, in fact it’s there so often it’s referred to as the Australian high.

It can sit there for days, or even weeks, and stop cold air flowing up from the south, which leads to periods of clear, hot weather, in other words, perfect beach weather.

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