Aridity in hot desert regions is mainly driven by a combination of high temperatures, low humidity, and insufficient rainfall.

Regions such as the Sahara and the Arabian Desert exemplify extreme aridity. The high temperatures in these areas are a primary factor contributing to their dry conditions. The intense heat leads to rapid evaporation of surface water, significantly diminishing the moisture available in the atmosphere for precipitation. Consequently, these regions experience very low levels of rainfall, which is a defining feature of arid environments.

Another critical factor influencing aridity is the low humidity present in hot deserts. Humidity measures the amount of water vapor in the air. Typically, the air in these regions is exceedingly dry, containing minimal water vapor. This dryness stems from the swift evaporation of any available water due to high temperatures. Low humidity not only hinders cloud formation but also reduces the likelihood of rainfall, further exacerbating the arid conditions.

The geographical positioning of these deserts also contributes to their dryness. Many hot deserts are situated within the subtropical high-pressure belt, where air descends. This descending air is associated with high pressure, which discourages cloud formation and precipitation, resulting in very limited rainfall in these regions.

Additionally, the scarcity of vegetation plays a significant role in maintaining aridity. Plants are vital to the water cycle, as they release water vapor into the atmosphere through a process known as transpiration. In hot deserts, the minimal presence of vegetation leads to reduced transpiration, further limiting the moisture available in the atmosphere and decreasing the chances of rainfall.

In summary, the aridity of hot desert regions arises from a combination of high temperatures, low humidity, limited rainfall, geographical location, and sparse vegetation. These factors interact in intricate ways, resulting in the extreme arid conditions that characterize these environments.