dry arid an area of land where less than 10 inches of rain falls per year Desert when a liquid turns into vapor or gas Evaporation water in the atmosphere reaching the surface of the earth (rain, sleet, snow frost, and dew) Precipitation the creation of new deserts and dry areas from moister lands by human activities like farming or draining away water Desertification rain falls on the sides of mountains that face a water source rather than on the sheltered sides of mountains Rain shadow a fan-shaped deposit of sedimentary materials at the mouth Alluvial fan a deep gully cut by an intermittent stream Arroyo a hill that rises abruptly from the surrounding area and has sloping sides and a flat top Butte a ridge or hill of wind-blown sand Dune carrying away broken pieces of rock (sediment) caused by weathering Erosion water under the ground, in spongy rocks and in cracks, crevices, caves and tunnels Groundwater a flat-topped elevation with one or more cliff-like sides Mesa an optical phenomenon creating the illusion of water Mirage a fertile area in a desert where groundwater can reach the surface Oasis finely divided solid material that settles to the bottom of a liquid Sediment a valley, gully, or riverbed that remains dry except during the rainy season Wadi change to survive a specific environment Adapt when a living thing remains still and inactive, as though asleep, to save energy and survive bad conditions Dormant catching the energy in sunlight and converting it into the energy in foods and nutrients for living and growing Photosynthesis active at night Nocturnal having fleshy tissues designed to conserve moisture Succulent a camel with two humps Bactrian a camel with one hump Dromedary continuous expanse of sand; sandy deserts Erg narrow band of grassland that separates the desert from the grasslands of the central African plains Sahel northwesterly wind on Arabian Peninsula causing frequent sandstorms Shamal low areas that may hold water; they lie in valleys Sinks contains gravel and some sparse vegetation; stony deserts Reg made up of bare rock; rock desert Hammad plants that appear only when there is rain; the rest of the time they lie dormant as hardy seeds. drought evaders/ephemerals plants that have developed many ways to prevent drying out. drought resisters people who move from place to place in the desert nomads moving from place to place in the desert nomadic 30 N and 30 S latitudes horse latitudes air at the equator that is has very light winds doldrums ridges running in the same direction as the wind is blowing. longitudinal dunes occur when one wind blows into the main wind at a right angle seif dunes occur when winds change directions many times. star dunes crescent shaped dunes, occur when the blown sands hit a barrier, like a rock. barchan dunes shallow lake beds playas formed by winds sweeping over arctic waters that are too cold to pick up moisture; the winds blow onto the coast creating very arid conditions. cold coastal deserts where people have drilled through the impermeable rock. well oasis where an earthquake has caused the layers of earth to shift and the water in the aquifer pushes it’s way up the slit caused in the impermeable rock. fault oasis where the wind has worn away the top soil and the bedrock exposing the aquifer to the surface. basin oasis layers of underground, permeable rock where water is found in deserts aquifer Formed when air at the doldrums or equator rises & spreads N and S to the horse latitudes becoming hot dry winds that dry out the lands they sweep across Subtropical desert Formed when an area is too far from the ocean winds for the moisture to make it all the way inland desert This is the entire vocabulary list for our Deserts Unit. I will have other units up by Wednesday, 10/12.