Friday, August 12, 2011

Desert

Desert
  • a land of extreme heat and dryness; sudden flash floods and cold nights
  • a harsh environment, often named 'Death valley', 'the place of no return'
  • very, very dry
    (even wettest deserts get less than 10 inches of precipitation per year)
  • only a few periods of rains per year with lots of time between them
  • during the day, temperature are as high as 100F ; but during the night, tempereature can fall till 40s and 50s.
    (Because deserts have only 10% to 20%  humidity to trap temperatures and have so little trees and other vegetation to cool down heat, the cool down rapidly when sun sets and heat up quickly after sun rises)
Types
  • Hot (main form of precipitation: rain)
    - includes: Thar, Sahara, Monte, Kalahari
  • Cold (main form of precipitation: snow or fog)
    - includes Namib, Iranian, Great Basin, Gobi
Location
  • many are found in bends along 30degrees latitude north and 30degrees latitude south.
  • some located by mountains are are caused by the 'rainshadow' effect.
    - As air moves up over a mountain range, it gets cold and loses its ability to hold moisture - so its rains or snow. When ari moves over to the other side of the mountain, it gets warmer. Warm air can hold lots of moisture, so it doesn't rain as much and a desert is formed.



Deserts of the world



World's Largest Deserts
Desert Location Square
Miles
Square
Kilometers
Sahara North Africa 3,500,000 9,065,000
Gobi Mongolia-China 500,000 1,295,000
Kalahari Southern Africa 225,000 582,000
Great Victoria Australia 150,000 338,500
Great Sandy Australia 150,000 338,50




Deserts of North America
Name
Location
Size Physical
Features
Some Plants & Animals Special Facts
Chihuahuan
North Central Mexico and Southwestern United States (Arizona, New Mexico, Texas)
175,000 mi2
455,000 km2
High plateau covered by stony areas and sandy soil. Many mountains and mesas. cacti, chihuahuan flax, creosote bush, lechuguilla, mesquite, mexican gold poppy coyote, diamondback rattlesnake, javelina, kangaroo rat, roadrunner Largest North American desert. Big Bend National Park located here; more species of birds seen in Big Bend than in any other National Park in the U.S.
Great Basin
Western United States (Idaho, Nevada, Oregon, and Utah)
158,000 mi2
411,000 km2
Covered by sand, gravel, and clay. Many moutains ranges, basins, and large expanses of salt flats. greasewood, sagebrush, shadscale bighorn sheep, jackrabbit, pocket mouse, poor-will, pronghorn antelope, sage thrasher, side-blotched lizard Great Salt Lake located here.
Mojave
Southwestern United States (Arizona, California, Nevada)
25,000 mi2
65,000 km2
Covered by sandy soil, gravelly pavement, and salt flats. creosote bush, desert sand verbena, joshua tree, mesquite bighorn sheep, chuckwalla, coyote, jackrabbit, sidewinder, zebra-tailed lizard Death Valley located in this desert.
Sonoran
Southwestern United States (Arizona, California) and parts of Mexico (Baja Peninsula, Sonora)
120,000 mi2
312,000 km2
Covered by sand, soil, and gravelly pavement. Gets more rain than any other North American desert. agave, coulter's globemallow, creosote bush, desert mariposa lily, mesquite, ocotillo, paloverde, saguaro coati, elf owl, gila monster, kangaroo rat, pack rat, roadrunner, sidewinder, tarantula Most complex animal-plant community of any desert.



Desert Plants
  • home to many living things
  • second only to tropical rainforests in the variety of plant and animal species that live there
  • main adaptions to survive in the harsh conditions are ability to collect and store water and features that reduce water loss
  • Includes old man cactus, prickly pear cactus, dragon tree,






Desert animals
  • must adapt to the harsh conditions to survive; some never drink but gets their water from seeds and plant,  some sleep during the hot day and only comes out at night to eat and hunt, some rarely spend time above ground
  • Includes addax, dingo, fat sand rat, fennec fox




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