THE CLIMATE TROPICAL DESERTS Flashcards
What is meant by the term tropical deserts?
Tropical deserts are areas that have very high temperatures and receive less than 250 mm of precipitation a year.
Name the largest tropical desert found in North Africa
It is called the Sahara Desert.
Name the desert found on the west coast of Africa.
It is called the Namib Desert.
Name the desert found on the west coast of South America.
It is called the Kalahari Desert.
List the three main causes of tropical deserts.
The three main causes are a) been under the sinking limb of the Hadley cell, b) been in a rainshadow area and c) been near to cold ocean currents.
The sinking limb of the Hadley cell causes what type of surface pressure system.
The sinking limb of the Hadley cell causes a high pressure system. It is sometimes called the sub-tropical high pressure system.
Between which latitudes is the sub-tropical high pressure belt found.
Sub-tropical high pressure areas are located between latitudes 25” and 35” N and S of the equator.
Name the casestudy that would be used to answer a 7 mark question on tropical deserts.
The casestudy would be the Sonoran Desert.
Describe the location of the Sonoran Desert.
The Sonoran Desert is located in the South West of the USA between the 25 and 33 degrees north of the equator.
Name the mountain range to the west of the Sonoran Desert.
It is the Sierra Nevada Mountain Range.
Is the Sonoran Desert located underneath the sinking or rising limb of the Hadley cell.
It is located underneath the sinking limb of the Hadley cell.
Describe the annual variations in day time temperatures for Yuma which is located in the Sonoran Desert.
Yuma has very high daytime temperatures in July it can reach 42 degrees C and in January it can be as high as 18 degrees C.
Describe how low the temperature at Yuma can fall at night.
Temperatures at night can drop to 25 degrees C in the July and as low as 5 degrees C in January.
What is the annual rainfall total for Yuma which is located in the Sonoran Desert.
The annual rainfall total is 100 mm.
What is the highest monthly rainfall total for Yuma which is located in the Sonoran Desert.
The maximum monthly for a single month is 10 mm.
The Sonoran Desert is situated beneath the sinking limb of the Hadley cell. Explain how this leads to its high temperatures.
Due to the sun been high in the sky and its position under the sinking limb of the Hadley cell. As the air descends its temperature increases leading to a decrease in its relative humidity and a cloud free sky. Therefore, the surface of the desert absorbs large amounts of insolation. The surface then emits longwave radiation, which is absorbed by the atmosphere causing very high temperatures.
The Sonoran Desert is situated beneath the sinking limb of the Hadley cell. Explain how this leads to low amounts of annual rainfall.
As the air descends in the sinking limb of the Hadley cell its temperature increases and its relative humidity decreases, which leads to a cloud free atmosphere and very little rainfall
The Sonoran Desert is situated on the leeward side of the Sierra Nevada Mountain range. Explain how this leads to low amounts of annual rainfall.
When the winds blow from the west it is forced to rise over the Sierra Nevada Mountains range. As the air ascends it cools which results in high levels of rainfall on the windward side of this mountain range. This means that when the air descends on the leeward side of the mountain range it warms up with little water vapour and with a lower relative humidity, therefore it contains very little water moisture that can be used to form rain.
Explain why the Sonoran Desert experiences relatively low temperatures at night.
The temperatures are low at night as a result of cloudless skies. Without the absorbent effect of the clouds, most of the outgoing longwave radiation emitted from the surface of the desert passes directly through the atmosphere and escapes to space.
Explain why the Sonoran Desert experiences lower temperatures at night in January then in July.
The temperatures at night are lower in January because the nights are longer in the winter and there are no clouds. Therefore, more longwave radiation escapes to space which has a cooling effect on the air temperature.
Explain why the Sonoran Desert experiences higher daytime temperatures in July than in January.
The July temperatures in the day are higher because the sun is higher in the sky and the days are longer, this means that more insolation is absorbed by the desert surface. Therefore, it emits more longwave radiation which warms the air.
