Atmospheric Cells

The Three-Cell Model

Air circulates in the atmosphere in three atmospheric cells (Hadley, Ferrel, and Polar Cells). Air circulates within these cells throughout the troposphere (the atmosphere from the surface to between 10 and 15 km high).

Hadley Cell (0° to 30° N and S of the Equator)

Location: Extends from the equator up to 30° in both hemispheres.
Features:

• High temperatures at the equator, caused by more concentrated solar radiation, create low pressure as warm air rises.
• As air rises, it cools, leading to condensation and heavy rainfall around the equator.
• The air moves towards the poles at high altitudes, cools, and sinks at about 30° north and south, creating high-pressure areas.
• As moisture in the sinking air falls at the equator, it is dry, and few clouds form, resulting in subtropical deserts (e.g., the Sahara Desert).

Ferrel Cell (30° to 60° N and S)

Location: Found between 30° and 60° latitudes in both hemispheres.
Features:

• Air in these cells moves poleward and eastward near the surface.
• Rising warm air from the subtropical high meets the cold air from the poles at around 60° N and S, leading to precipitation.
• Contributes to the weather in mid-latitude areas, characterised by more variable weather conditions.

Polar Cell (60° to 90° N and S)

Location: Extends from 60° latitude to the poles.
Features:

• Cold air at the poles sinks and flows towards lower latitudes.
• The air warms as it travels southward, rising again around 60° latitude, forming clouds and precipitation.
• Associated with frigid polar climates.