Answer to Question 1
ANSWER: The major dry regions of the world can be divided into two primary categories. The first includes those sections of the subtropics (between latitude 15 and 30) where the sinking air of the subtropical anticyclones produces generally clear skies. The second is found in the continental areas of the middle latitudes. Here, far removed from a source of moisture, areas are deprived of precipitation. Dryness here is often accentuated by mountain ranges that produce a rain shadow effect. Kppen divided dry climates into two types based on their degree of dryness: the arid (BW) and the semi-arid, or steppe (BS). These two climatic types can be divided even further.
Answer to Question 2
ANSWER: In many areas (especially within India and Southeast Asia), the marked variation in precipitation is associated with the monsoonthe seasonal reversal of winds. The Asian monsoon circulation is due in part to differential heating between landmasses and oceans. During winter in the Northern Hemisphere, winds blow outward, away from a cold, shallow high-pressure area centered over continental Siberia. These downslope, relatively dry northeasterly winds from the interior provide India and Southeast Asia with generally fair weather and the dry season. In summer, the wind-flow pattern reverses as air flows into a developing thermal low over the continental interior. Humid air from the water rises and condenses, resulting in heavy rain and the wet season.