global atmospheric circulation

• The sun’s energy is concentrated at the equator, making the temperature hot. Hot air rises, creating a low-pressure belt. When the air reaches high altitudes it moves north and south.
• As the air moves away from the equator it cools and begins to sink. Sinking air creates a high-pressure belt at thirty degrees north.
• Wind is the movement of air from high pressure to low pressure. When sinking air reaches the surface, some move back to the equator as trade winds. This completes the Hadley cell. Some air moves north as westerlies to start the Ferrel cell.
• Winds moving North meet cold winds from the Polar cell. The warmer ferrell cell winds are forced to rise. This forms another low-pressure belt at sixty degrees north.
• Air moving north in the Polar cell cools and sinks at 90 degrees north. This creates high pressure. Winds move from high pressure at 90 degrees north to low pressure at 60 degrees north.
• The weather at the equator is hot and wet because of concentrated solar insolation from the sun. Hot air rises, creating low pressure. It then cools and condenses to give predictable and conventional rainfall.
• At the high-pressure belt the weather is hot and dry because sinking air loses moisture, giving clear blue skies and little precipitation. IT is hot because it is still close to the equator.
• At the low pressure belt the weather is mild and wet because air moving north in the Ferrel cell is forced up when it meets cold air from the Polar cell. It cools and condenses, giving frontal rainfall
• In the poles the weather is cold and dry because the sun's insolation is spread out over a large area, making it cold. sinking air in the polar cell gives high pressure and dry weather