geography (the atmosphere as a global system)

What is the atmosphere?

The layer of gases surrounding Earth.

Why is the Earth heated unevenly?

The equator receives more concentrated solar energy than the poles because of the angle of the incoming sunlight.

What does uneven heating cause?

Differences in temperature and air pressure, causing air to move and creating global atmospheric circulation.

What is the main purpose of global atmospheric circulation?

To redistribute heat energy around the Earth, moving heat from warmer areas towards cooler areas.

What are the three atmospheric circulation cells in each hemisphere?

Hadley Cell, Ferrel Cell and Polar Cell.

Where is the Hadley Cell found?

Between 0* and 30* latitude.

Where is the Ferrel Cell found?

Between 30* and 60* latitude.

Where is the Polar Cell found.

Between 60* and 90* latitude.

What happens at the equator?

Strong solar heating causes warm air to rise, creating low pressure.

What happens when air rises?

It expands and cools, causing water vapour to condense, leading to cloud formation and rainfall.

What happens around 30* N/S?

Air sinks, creating high pressure and dry conditions.

What happens around 60* N/S?

Air rises, creating low pressure and wetter conditions.

What happens around the poles?

Cold, dense air sinks, creating high pressure and dry conditions.

What is the relationship between low pressure and rainfall?

Rising air cools and condenses, forming clouds and making rainfall more likely.

What is the relationship between high pressure and rainfall?

Sinking air warms and becomes drier, so cloud formation and rainfall are less likely.

Why are tropical rainforests common around the Equator?

The Equator is very hot, so air rises. This creates low pressure and heavy rainfall.

Why are many deserts found around 30* N/S?

Air sinks around 30*, creating high pressure and dry conditions.

What is the relationship between low pressure and rainfall.

Low pressure causes rising air, which cools and condenses, causing rainfall.

What is the relationship between high pressure and rainfall?

High pressure causes sinking air, which becomes warmer and drier so there is little rainfall.

What are ocean currents?

Large movements of seawater that redistribute heat.

How do warm ocean currents affect climate?

They move heat towards higher latitudes, warming nearby areas.

How do prevailing winds affect ocean currents?

They help drive surface ocean currents.