The Sahara Desert is so dry primarily because of its location in a specific atmospheric region where weather patterns actively prevent rainfall.
The Atmospheric Reason for Sahara's Dryness
Located in the horse latitudes under the subtropical ridge, the Sahara falls within a significant belt of semi-permanent high atmospheric pressure. This specific meteorological condition leads to a process described in the provided reference:
- Descending Air: In this high-pressure zone, air from the upper troposphere usually descends.
- Warming and Drying: As this air descends, it gets compressed and warms up. This process significantly dries the air in the lower troposphere.
- Preventing Clouds: The dry, descending air prevents cloud formation.
- Lack of Precipitation: Without clouds, there is little to no rainfall, leading to the extremely arid conditions characteristic of the Sahara Desert.
Essentially, the large-scale atmospheric circulation pattern over the Sahara creates a constant state of dry, clear conditions, making it the world's largest hot desert.
