NATS 1750 Lecture Notes - Lecture 17: Desert Varnish, Suspended Load, Caliche
30 Dec 2019
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Document Summary
Deserts are so dry that they support vegetation on no more than 15% of the surface. The average annual rainfall is less than 25cm/year. Deserts cover about 25% of the earth"s surface. Other types of deserts: subtropical deserts, coastal deserts, and rain-shadow deserts. Subtropical deserts form because they lie beneath the portion of an atmospheric circulation cell (the. Hadley cell) where dry air descends and warms. Rain-shadow deserts form when moist air rises and drops rain on the coastal side of a mountain range. On the leeward side of the mountains, the air is dry too dense to rise and produce rain clouds. Coastal deserts form when cold ocean currents cool and moisten the air along the coast; this air is. Physical weathering : joints cause rocks to break apart. Chemical weathering occurs more slowly in dry climates, but essentially rots the rock into piles of unconsolidated sediment. Desert varnish = shiny, rusty-brown coating or iron oxide.
