The distribution of air pressure in the atmosphere varies both vertically and horizontally:

Vertical distribution
Air pressure decreases rapidly as you move up through the atmosphere, dropping about 1 millibar for every 10 meters of elevation. This is because the air is less dense at higher altitudes, where temperatures are lower and pressure is lower.

Horizontal distribution
Air pressure is affected by temperature, which causes air to rise in warmer areas and sink in colder areas. This creates areas of high and low pressure. For example, the poles have high pressure, while the equatorial regions have low pressure.

Wind
The horizontal movement of air in response to pressure differences is called wind.

Air currents
Vertical or nearly vertical moving air is called air currents.

Water vapor
The amount of water vapor in the air also affects air pressure, as water vapor is lighter than dry air.

Vertical Distribution of Air Pressure
Air pressure decreases with altitude due to the thinning of the atmosphere. As you go higher in the atmosphere, there are fewer air molecules above you, resulting in lower pressure.
- Troposphere: In this layer, which extends up to about 8-15 km, air pressure is highest. Weather phenomena occur here.
- Stratosphere: As we move up into the stratosphere, air pressure continues to decrease. This layer contains the ozone layer, which absorbs UV radiation.
- Mesosphere: In this layer, air pressure drops even further, and it is where meteors burn up upon entering the Earth's atmosphere.
- Thermosphere: The pressure is extremely low in this layer, despite the high temperatures. The few air molecules present are very energetic.
Horizontal Distribution of Air Pressure
Horizontal air pressure distribution varies across the Earth's surface due to several factors, including temperature, altitude, and humidity.
- High-Pressure Areas: These are regions where air is sinking, leading to clearer skies and stable weather. Typically found at 30° north and south latitudes (subtropical highs).
- Low-Pressure Areas: These occur where air is rising, often leading to cloud formation and precipitation. Commonly found at the equator (intertropical convergence zone) and at mid-latitudes.
- Pressure Belts: The Earth has distinct pressure belts:
- Equatorial Low: Characterized by low pressure due to intense heating.
- Subtropical High: High pressure resulting from descending air.
- Subpolar Low: Low pressure caused by the meeting of cold and warm air.
Understanding the vertical and horizontal distribution of air pressure is crucial for predicting weather patterns and phenomena.