Hot Deserts

Specification

Key words

Ecosystems

A biological environment consisting of all the living organisms (biotic) within a particular area and the nonliving (abiotic) that interact with the organisms e.g. weather, soil, air and water.

Biome

Is a major ecological community with distinct climate, animals and plants. A biome is made of many similar ecosystems. 

The climate of a hot desert

Characteristics and climate of deserts

Deserts have extreme temperatures. During the day the temperature may reach 50°C, when at night it may fall to below 0°C. Deserts have less than 250 mm of rainfall per year. The rain can be unreliable. Most deserts are found between 20° and 35° north and south of the equator.

• Climate is extremely hot and temperature remains more than 40 degrees for most time of the day. However, the hot desert become cold as the temperature falls below 0 degree.
• Climate is very dry with negligible humidity. The average rainfall is 250 mm a year.

Rainshadow Effect

Rain shadow deserts are created when mountain ranges lie parallel to moist, coastal areas. Prevailing winds moving inland cool as air is forced to rise over the mountains. Carried moisture falls on slopes facing the winds. When the winds move over the crest and down the far side, they are very dry.

The Hadley Cell

The Hadley Cell is a global scale tropical atmospheric circulation that features air rising near the Equator, flowing poleward at a height of 10 to 15 kilometers above the earth’s surface, descending in the subtropics, and then returning equatorward near the surface.

Namib Desert

• NAMIB DESERT– Namibia (West of Kalahari)
• Over 1,600 km of coast along SW of Africa, including Angola, Namibia and South Africa, 50 to 160 km wide inland to the Great Escarpment (edge of desert)
• 81,000 square kilometers
• Characterised by some of the largest sand dunes in the world
• One of the oldest deserts in the world

Plants

The southern Namib is home to over 600 species of plants, the central Namib 400 species and some 1,000 species in the northern Namib.

How have camels adapted to the desert?

Camels have been domesticated for at least 3500 years and have long been valued as pack animals. They can carry large loads 25 miles a day. Camels have adapted to survive hot deserts because they:

• have humps to store fat which a camel can break down into water and energy when nourishment is not available;
• rarely sweat, even in hot temperatures, so when they do take in fluids, they can conserve them for long periods of time;
• have large, tough lips enable them to pick at dry and thorny desert vegetation;
• have broad, flat, leathery feet to spread their weight and provide protection from hot sand; 
• lose little water through urination and perspiration; and
• have slit-like nostril and two rows of eyelashes to protect themselves from the sand.

How have fennec foxes adapted to the desert?

The fennec fox is the smallest of all fox species. They are found in the Sahara Desert and elsewhere in North Africa. They are nocturnal, which helps them deal with the heat of the desert environment. They have also made some physical adaptations to help as well. For example, they:

• have thick fur on feet protecting them from the hot ground;
• have large, bat-like ears radiate body heat and help keep them cool;
• have long, thick hair that insulates them during cold nights and protects them from the hot sun during the day;
• have light coloured fur to reflect sunlight and keep their bodies cools. 

How have kangaroo rats adapted to the desert?

A kangaroo rat is a rodent that is found in desert areas in south-western North America. Desert kangaroo rats live in areas with loose sand, often dune terrain. Kangaroo rats have made several adaptations to enable them to survive in the desert, including:

• getting moisture from their seed diet;
• living in burrows during the day to avoid extreme heat;
• having large back legs that allow them to jump almost 3m to avoid predators;
• having large ears, which enables them to hear approaching predators.

Land Use