The Sahara, Arabian, and Sonoran deserts, among other large hot deserts of the Northern Hemisphere, are positioned strategically along the western shores of continents. This geographic pattern is the outcome of particular meteorological and geographical variables rather than a coincidence.

Influence of Cold Ocean Currents: The existence of cold ocean currents along these western shores is one of the main causes. The air above them is cooled by cold currents such as the California and Canary currents. This colder air warms up and loses relative humidity as it passes over the land, creating dry, arid conditions that help deserts grow.

High Pressure Systems: The horse latitudes, or subtropical high-pressure belts, are important. Dry air descends from these high-pressure zones, which are located about 30 degrees north and south of the equator. This air warms as it falls, preventing precipitation and the formation of clouds. This produces the dry conditions found in deserts.

Rain Shadow Effect: Due to the rain shadow effect, mountain ranges close to the western shore might promote the formation of deserts. Cooling as it climbs the windward side of mountains, moist air from the ocean releases moisture as rain. Inland desert conditions result from the dry air that descends on the leeward side.

Continentality: The western regions of continents benefit from their distance from large bodies of water, which results in lower levels of precipitation and moisture. This “continentality” adds to the dry weather that characterizes deserts.

Combining Factors: Along the western coasts of continents in the Northern Hemisphere, deserts flourish due to a combination of factors including high pressure systems, rain shadow effects, cold currents, and continentality.