Global Atmospheric Circulation

What is global atmospheric circulation?

The movement of air around the atmosphere to redistribute heat.

What is the formula for global atmospheric circulation?

Latitude + solar energy + air pressure = air movements around the world.

What is latitude?

Coordinates going from North to South specifying point on Earth from 0-90, with 0 being the equator and 90 being North and South Pole.

How does latitude correlate with the temperature?

A lower latitude leads to a warmer temperature.

How does latitude aid atmospheric circulation?

The latitude changes the solar energy through the angle of incidence.

At 0 there is a small angle of incidence therefore solar energy spreads over a small area making it more concentrated.

At 90 there is a large angle of incidence therefore solar energy spreads over a large area making it less concentrated. Due to the curvature of the Earth.

How does the distance aid atmospheric circulation?

The atmosphere thickness stays the same all round.

At the equator, solar energy travels a shorter distance through the atmosphere therefore there is a low chance of solar energy being rejected by clouds and gases back to space.

At the poles, solar energy travels a longer distance through the atmosphere therefore there is a high chance of solar energy being rejected by clouds and gases back to space.

What is atmospheric pressure?

The weight of the air, and the force it exerts on the ground.

When air is heated, it increases energy in the air making it less dense, therefore it rises. So there is lower pressure on the ground.

When air is cooled, its denser therefore it sinks and exerts more force on the ground. So there is a higher pressure on the ground.

How do convection currents work?

1. Ground heats up air above it (infrared)

2. Therefore hot air is less dense so it rises.

3. Air is far away from the ground so it cools down

4. Therefore cold air is denser so it sinks

How do convection currents affect global atmospheric circulation?

They facilitate the transfer of heat from warmer, denser regions to cooler, less dense areas.

How does the sun heat up our Earth?

The sun doesn’t directly heat the Earth, (as UV is bad at heating air) instead the ground does:

• Short wave radiation (UV) is emitted from the sun that shines onto the ground

• The ground absorbs it and repels it in long wave radiation (infrared) heating the air.

How is wind caused?

• Wind is caused when air travels from an area of high to low pressure.

What is the coriolis effect?

• As the winds travel above the Earth’s surface + the planet below spins, wind follows a curved path.

• North hemisphere curve to right

• South Hemisphere curve to left

What are jet streams?

• At the boundary of main circulation cells, there is a significant temperature differences.

• This impacts air movement and weather systems.

Hadley cell

• From 0 to 30 latitude

• Thermally direct (powered by heat)

  1. Ground heated by Sun at Earth is most intense therefore heats air, less dense eventually rises.

  2. Air is pushed northwards by more rising air beneath it.

  3. Air is cooled as it’s far away from the ground therefore more dense, sinks back to Earth.

  4. Air pushed along by more sining air.

Ferrel cell

• From 30 to 60 latitude

• Thermally indirect (powered by other cells)

  1. Air is sinking at 30 degree because of the Hadley cell.

  2. Air is rising at 60 degree because of the Polar cell

Polar cell

• From 60 to 90 latitude

• Thermally direct (powered by heat)

  1. Air is cold at the poles (less intense solar energy) therefore more dense and air sinks.

  2. Air is heated as it is pushed along the ground.

  3. Hot air = less dense therefore it rises

  4. Air is pushed northwards by more rising air.

Subtropical jetstream?

Between the ferrel and hadley cell, trapping temperature air

Polar jetstream?

Between hadley and polar cell, trapping polar air