Why do deserts have such low rainfall?

Deserts have low rainfall due to their location in high-pressure zones, where dry air descends and inhibits cloud formation. Many deserts, like the Sahara, are situated at around 30° latitude, where these conditions are prevalent. Others, such as the Atacama Desert, are in rain shadows of mountains, where moist air loses its water content before reaching the desert. These factors create arid climates with minimal precipitation.