Global Atmospheric Circulation

Global Atmospheric Circulation

1. Global Atmospheric Circulation is the large-scale movement of air, by which heat an moisture is distributed around the Earth’s surface. (Or this can be simply defined as the movement of the atmosphere).

   • The Earth's Climate Zones
     • Polar: 90°N Temperate: 60°N Tropical: 30°N Equator: 0° Tropical: 30°S Temperate: 60°S Polar: 90°S

2. Key Terms

   • Latitude
     • Latitude is how far north or south a place is from the Equator. Other than the Equator there are four main lines of latitude, those being: the Arctic Circle, Tropic of Cancer, Tropic of Capricorn, and the Antarctic Circle. Latitude affects weather as the further you are from the Equator, the colder the weather is.
   • Wind
     • Wind is the movement of air from areas of High to Low Pressure - always.
   • Synoptic Chart
     • Synoptic Charts (weather maps) provide information on the distribution, movement and patterns of air pressure, rainfall, wind and temperature.
   • The Equator
     • The Equator is an intersection on Earth’s surface that is equidistant from both the North and South Poles, meaning it divides the Earth into the Northern and Southern Hemispheres.

3. Areas of High and Low Pressure

   • Air that is sinking towards the ground forms areas of HIGH PRESSURE, such as the North Pole. High Pressure brings dry, sunny days.
   • Air that is rising upwards from the ground forms areas of LOW PRESSURE, such as the areas surrounding/on the Equator. Low Pressure brings clouds, rain and wind.
     • 1. Air is heated up by the Earth’s surface and rises upwards. 2. Once it reaches the atmosphere, it moves outwards and begins to cool. 3. Then, when it becomes cool enough, the air sinks back down to the surface. 4. When the air reaches the surface of the Earth, it moves outwards along the surface and begins to warm up.
   • The air moves from areas of High to Low pressure to fill the gaps in the cycle enabling it to continue. This wind moves along the ground or high up in the atmosphere.

4. The Global Circulation Model

   • Surface winds/winds on the ground are altered by the Earth’s rotation. They curve as they move from areas of High to Low Pressure and this is known as the Coriolis Effect.
     • The Coriolis Effect is the result of Earth's rotation on weather patterns and ocean currents.

5. The Curvature of The Earth

   • The Sun’s rays are directly concentrated at the Equator, but spread out at the Poles. Therefore, as the Sun’s rays are distributed further in the Poles and the area heated is larger, more insolation (the sun’s energy) is lost which results in cooler at high latitudes.
     • Insolation or Incoming Solar Radiation is the energy from the sun.