Slide 1: DESERTS D. Aditya ENGLISH PROJECT
A desert is a landscape or region that receives very little precipitation. Deserts are defined as areas with an average annual precipitation of less than 50cm/yr (10 in), or as areas where more water is lost by evapotranspiration than falls as precipitation. : A desert is a landscape or region that receives very little precipitation. Deserts are defined as areas with an average annual precipitation of less than 50cm/yr (10 in), or as areas where more water is lost by evapotranspiration than falls as precipitation. Desert-definition Judean desert
In the Köppen climate classification system, deserts are classed as BWh (hot desert) or BWk (temperate desert). In the Thornthwaite climate classification system, deserts would be classified as arid megathermal climates. : In the Köppen climate classification system, deserts are classed as BWh (hot desert) or BWk (temperate desert). In the Thornthwaite climate classification system, deserts would be classified as arid megathermal climates.
Slide 4: Deserts are part of regions that, on an average annual basis have moisture deficit Deserts are located where vegetation cover is sparse to almost non-existent
Slide 5: Desert features During daylight most of the sun's heat reaches the ground, and as soon as the sun sets the desert cools quickly by radiating its heat into space. Deserts take up about one third (33 percent) of the Earth's land surface. In hot deserts the temperature in the daytime can reach 45 °C/113 °F or higher in the summer, and dip to 0 °C/32°F or lower in the winter
Slide 6: Deserts are often composed of sand and rocky surfaces. Sand dunes called ergs and stony surfaces called hamada surfaces compose a minority of desert surfaces. Many deserts are formed by rain shadows; mountains blocking the path of precipitation to the desert. The soil is rocky because of low weathering
Slide 7: Cold deserts (also known as polar deserts) have similar features, except the main form of precipitation is snow rather than rain.
Antarctica is the world's largest cold desert (composed of about 98 percent thick continental ice sheet and 2 percent barren rock). Cold & Hot deserts-
World distribution
Slide 8: Desert forms Mountain and basin deserts In general, there are six forms of deserts: Regs, which consist of rock pavements Badlands, located at the margins of arid lands Hamada deserts, which consists of plateaus Ergs, which are formed by seas Intermontane Basins
Slide 9: Antartic-13,829,430 sq. km
Arctic-13,700,000+ sq. km
Sahara-9,100,000+ sq km
Arabian desert-2,330,000 sq km
Gobi-1,300,000 sq km
Kalahari-900,000 sq km
Patagonian-670,000 sq km
Great Victoria desert-647,000 sq km
Syrian Desert-520,000 sq km
Great Basin Desert-492,000 sq km Worlds major deserts
Chapter 3 : Chapter 3 Climates of the World’s Deserts
Some General Properties : Some General Properties Meteorological characteristics
Surface characteristics
Vegetation characteristics
Variety of Properties : Variety of Properties Cold deserts and hot deserts
Deserts with winter precipitation and deserts with summer precipitation and deserts with virtually no precipitation
Perpetually foggy deserts and deserts with near the maximum possible sunshine
Barren deserts and heavily vegetated deserts
Sand-dune deserts and deserts with rocky plains
Desert Climate Types : Desert Climate Types
Warm Versus Cold Deserts : Warm Versus Cold Deserts
Slide 16: Climate % arid lands Coldest mo Warmest mo Examples
Hot 43 10-30 >30 Central Sahara
Great Sandy (Aust)
Mild Winter 18 10-20 10-30 Southern Sahara
Kalahari
Mexico Deserts
Simpson (Aust)
Cool Winter 15 0-10 10-30 Northern Sahara
Atacama
Mojave
Cold Winter 24 <0 10-30 Canadian Prairie
Gobi
Turkestan
Deserts of China
Great Basin
Coastal/Foggy Desert : Coastal/Foggy Desert Summer temperatures are not especially high, but the winters are not cold because the ocean is close
Can be very uncomfortable because of high humidity
Temperature (solid) and Relative Humidity (dashed), at Different Distances From Namib Desert Coast : Temperature (solid) and Relative Humidity (dashed), at Different Distances From Namib Desert Coast 5 km from coast 30 km from coast Far inland FOG
Precipitation : Precipitation
Seasonality of Precipitation : Seasonality of Precipitation (some/none of each)
Desert Temperature : Desert Temperature Why is it high?
Lack of evaporation from surface
Lack of vegetation (transpiration)
Not much cloud cover
Desert Winds : Desert Winds Subtropical deserts
- High pressure areas are generally characterized by weak winds
- Thunderstorms can produce high winds
- Mid-latitude disturbances (lows) with high winds can penetrate into deserts
Cold deserts in mid-latitudes, experience mid-latitude cyclones (lows) that can have strong winds
Lack of vegetation – near-surface winds higher
Winds are very desiccating – high temperature coupled with high winds
Desert Humidity : Desert Humidity Relative humidity can be as low as a few percent, or as high as 100% (foggy coastal desert)
Specific humidity
Compared to hot humid tropics, desert air is drier
But desert air of 95 F and 15% RH has more water vapor than does saturated air at 32 F in a winter storm
Slide 24: Mojave
Slide 26: Northern Chihuahuan Desert
The Deserts of Africa : The Deserts of Africa
African Deserts : African Deserts
Monthly Precipitation : Monthly Precipitation
Monthly Precipitation : Monthly Precipitation
The Deserts of North America : The Deserts of North America
Monthly Precipitation : Monthly Precipitation
The Deserts of South America : The Deserts of South America
Orography of Southern South America : Orography of Southern South America
Monthly Precipitation : Monthly Precipitation
Australian Deserts : Australian Deserts
Orography of Australia : Orography of Australia
Monthly Precipitation : Monthly Precipitation
Asian Deserts : Asian Deserts
Slide 51: Desert fauna and flora Deserts have a reputation for supporting very little life, but in reality deserts often have high biodiversity. Some fauna includes the Coyote Jack rabbit Kangaroo rat These animals adapted to live in deserts are called xerocoles.
Slide 52: Some flora includes …… Shrubs Most desert plants are drought- or salt-tolerant, such as xerophytes Prickly Pear cactus Brittlebush Desert Holly
Slide 53: Saguaro grow slowly but may live up to 200 years. When 9 years old, they are about 15 centimeters (6 in) high. The giant saguaro cacti of the Sonoran Desert provide nests for desert birds and serve as "trees" of the desert After about 75 years, the cacti develop their first branches. When fully grown, saguaro cacti are 15 meters tall and weigh as much as 10 tons.
“What makes the desert beautiful is that somewhere it hides a well.” : “What makes the desert beautiful is that somewhere it hides a well.” Antoine de Saint-Exupery
Slide 55: Thank you