context: The Sahara is the world's largest low-latitude hot desert. The area is located in the horse latitudes under the subtropical ridge, a significant belt of semi-permanent subtropical warm-core high pressure where the air from upper levels of the troposphere tends to sink towards the ground. This steady descending airflow causes a warming and a drying effect in the upper troposphere. The sinking air prevents evaporating water from rising and, therefore, prevents the adiabatic cooling, which makes cloud formation extremely difficult to nearly impossible.
question: మేఘాలు ఏర్పడడాన్ని ఏది కష్టతరం చేస్తుంది?
answers: sinking air