Why Do H and L Letters Appear on Weather Maps?

What Crafty Clover says in this video

Intro

Hi, weather watchers! I'm Crafty Clover! Let's discover something amazing. Why do H and L letters appear on weather maps?

The Big Idea

On a weather map, a big H marks the center of an area of high pressure. A big L marks the center of an area of low pressure. They are the main characters in the weather story, and they help us guess what is coming.

H Marks High Pressure

Step one: H means high. An H sits where the air pressure is higher than all around it. Sinking air there often means fair weather.

L Marks Low Pressure

Step two: L means low. An L sits where the air pressure is lower than all around it. Rising air there often brings clouds and rain.

Winds Flow Between

Step three: winds flow between them. Air tries to move from high pressure toward low pressure. Earth's spin bends that flow, so winds swirl around highs and lows.

A Closer Look

Let's take a closer look at a weather map! The H shows a high-pressure center. The L shows a low-pressure center. And the lines around them are isobars.

Quick Facts

Quick facts! Many maps print H in blue and L in red. In the northern half of the world, winds spin one way around highs and the other way around lows. Forecasters track where the highs and lows move, because the weather moves with them. Maps often print the pressure number beside each H and L.

Think Like a Scientist

Now, think like a scientist! Draw a pretend weather map on paper. Add H and L stickers, or write the letters. Draw arrows to show wind blowing from the H toward the L. Ask: which place would have clear skies, and which would be cloudy?

Outro

H and L are the big characters on a weather map. Science is amazing! Crafty Clover can be found on Amazon Books, Google Bookstore, and Apple Books. Available for purchase or download! Bye for now!