5. Many dry desert climates are found around \( 30^{\circ} \mathrm{N} \) and \( 30^{\circ} \mathrm{S} \) latitude. Which factor has the most influence on the formation of desert climates? A. dry air rising at \( 30^{\circ} \) latitudes B. dry air descending at \( 30^{\circ} \) latitudes C. low amounts of rainfall at other latitudes D. high rates of evaporation at the equator

The formation of desert climates around \(30^{\circ} \mathrm{N}\) and \(30^{\circ} \mathrm{S}\) is primarily influenced by the **subtropical high-pressure zones**. Here's a breakdown of the process: 1. **Equatorial Rising Air**: Warm air at the equator rises due to intense solar heating, creating the Intertropical Convergence Zone (ITCZ). 2. **Poleward Movement**: This rising air moves poleward at higher altitudes. 3. **Descending Air at 30° Latitude**: Around \(30^{\circ}\) north and south, the air begins to descend. As it descends, the air warms and its relative humidity decreases, leading to dry conditions. 4. **High Pressure and Low Precipitation**: The descending dry air creates high-pressure zones that inhibit cloud formation and precipitation, resulting in desert climates. Given these dynamics, **dry air descending at \(30^{\circ}\) latitudes** is the most influential factor in the formation of desert climates. **Answer:** B. dry air descending at \( 30^{\circ} \) latitudes