1. Air Pressure Highs and Lows

2. Can you feel air pressure?
When you take off or land in an aircraft, your ears may hurt or feel uncomfortable. This is because your eardrums can feel changes in air pressure as the aircraft moves quickly up and down.
But what is air pressure?

3. What is Air Pressure?
It is caused by the weight of all the air in the atmosphere pressing down on Earth.
It is also known as atmospheric pressure.
Air pressure changes with the height and also when air warms up or cools down.
Changes in air pressure cause changes in the weather and wind.

4. Differences in air pressure
Low Pressure
When warm air rises and expands, it leaves behind an area of lower pressure, because the upward- moving air is not pressing down so hard on the surface.

5. High Pressure
Areas of high pressure are formed where cool air is sinking back down, and pushes down harder.
>> see the diagram

6. There are many areas of high and low pressure above the Earth’s surface due to uneven surface heating.
Air moves from high pressure to low pressure forming winds.
As a result, the greater the difference between the high pressure and low pressure areas is, the higher the wind speed is.
Remember: Cools DOWN! Warms UP!

7. Low Pressure - Lows Pressure is different all over the world.
Lows are areas of low pressure with the lowest pressure at the center.
Lows usually bring wet, cloudy weather.

8. High Pressure - Highs
Highs are areas of high pressure with the highest pressure at the center.
Highs bring sunnier, and dry weather.
The way these move from day to day causes the changes in the weather.

9. Measuring Air Pressure
Air Pressure is measured in millibars (mb) on a barometer.
Meteorologists often use an instrument called a barometer to measure air pressure and the change in pressure
They track the movement of high and low pressure systems and the weather associated with them.