deserts

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Presentation Transcript

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

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