The three cell model Hadley cells, 0-30° latitude Solar heating at the equator warms the air above. The air rises and expands creating low pressure. The air travels to around 30°, cooling as it moves. At around 30° the cooled air sinks back to Earth to create an area of high pressure. Air moves from this high-pressure area to the equatorial low-pressure area. This is a thermally direct cell. Polar cells, 60-90° latitude The air above the poles is cold. The cold air sinks creating high pressure. The air moves towards the equatorial low-pressure zone, and warms up when it meets the land or ocean. At around 60° this warmed air rises. This is another thermally direct cell. Ferrel cells, 60-30° latitude The Ferrel cells are found between the Hadley and Polar cells. Cold air sinks near 30° and rises near 60°. The air at the Earth's surface flows northwards and is affected by the Coriolis force . The Ferrel cell is thermally indirect . Global circulation cells Jet streams These are very strong and fast-moving meandering wind bands. They are found at high altitudes, just below the tropopause , where the circulation cells meet. Jet streams are caused by pressure differences in the upper atmosphere and they move the weather systems around the planet.