A desert is an arid region characterized by extremely high or low temperatures, low rainfall and scarce vegetation. Water supports life, giving our earth the name living planet. It is very difficult to live in a place where there is no water to drink, no grass to feed the cattle and no water for the growth of grass.
It is a wonder that people who live in the deserts have learnt to have cope up with extremely harsh climates. Desert is either as hot as fire or as cold as ice.
Hence, depending on temperature, we can find hot deserts or cold deserts. People inhabit these lands, wherever little water is available to practice agriculture.
The Sahara desert covers a large part of North Africa. It has the following features:
- It is the world's largest desert. It covers an area of around 8.54 million square kilometers (which is more than the total area of India!!).
- It touches eleven countries which are as follows: Algeria, Morocco, Chad, Egypt, Libya, Mali, Mauritania, Niger, Sudan, Tunisia and Western Sahara.
- Besides being covered with vast stretches of sand, it has gravel plains and elevated plateaus with bare rocky surface. These rocky surfaces, at some places are more than 2500 m high.
Climate of Sahara Desert
The climate of the Sahara desert is scorching hot and parch dry. It has a short rainy season. Since the sky is cloudless and clear, the rate of water evaporation is greater than the rate of water accumulation. Hence there is water scarcity. The temperatures are as high as 50°C. This heats up the sand and the bare rocks, which heat up their surroundings. The nights may be freezing cold with temperatures nearing zero degrees Celsius.
Flora and Fauna in Sahara Desert
Flora: Vegetation in the Sahara desert includes cactus, date palms and acacia. We can find oasis at some places.
Fauna: The animal species found here are camels, hyenas, jackals, foxes, scorpions and many varieties of snakes and lizards.
People of Sahara Desert
The Sahara desert has been inhabited by different groups of people who are engaged in different activities. Among them are the Bedouins and the Tuaregs. These groups are nomadic tribes. They wear heavy robes to protect them from the harsh climate, i.e. dust storms and hot winds.
These tribes are engaged in animal rearing. Animals such as sheep, goats, camels and horses are reared for following purposes:
- Hides: These are used to make leather for belts, slippers and water bottles.
- Hair: This is used to make mats, carpets, clothes and blankets.
Growing date palms and agriculture: The oasis in the Sahara and Nile valley in Egypt supports settled population. Since water is available, people grow date palms. Other crops that are grown include rice, wheat barley and beans. Egyptian cotton that is famous worldwide is grown in Egypt.
Oasis: When wind blows away the sands, depressions are formed on land in deserts. Underground water reaches the surace in such depressions. That is how oasis is formed.These areas are fertile. People may settle around these water bodies. People may grow date palms and other crops. Sometimes the oasis may be abnormally large.
Changes in the desert
The discovery of oil is constantly transforming the Sahara desert. The discovery of oil has been made in Algeria, Libya and Egypt. Other important minerals found in this area include iron, phosphorus, manganese and uranium.
The changes due to business development and infrastructural development are also seen in this area.
- High rise buildings with gleaming glass facade tower over mosques, and superhighways crisscross the ancient camel paths.
- Trucks are replacing camels in salt trade.
- Tuaregs are seen acting as guides to foreign tourists.
- Many nomadic tribes are finding jobs in the field of oil and gas operations, and migrating to cities.
What is a Mirage?
Under a baking sun, a weary traveller trudges across a seemingly never-ending expanse of desert. Looking up, he suddenly spots something in the distance: a sparkling lake. He rubs his eyes. It's still there. Picking up the pace in glee he strides ahead… only for the water to melt into thin air.
You might think our traveller was hallucinating, but mirages are a naturally-occurring optical illusion. In cartoons, a mirage is often depicted as a peaceful, lush oasis lying in the shade of swaying palm trees, but in reality it is much more likely to look like a pool of water.
- The illusion results from the way in which light is refracted (bent) through air at different temperatures.
- Cold air is denser than warm air, and therefore has a greater refractive index. This means that as light passes down from cool to hot air, it gets bent upwards towards the denser air and away from the ground.
- To your eyes, these distorted rays seem to be coming from the ground, so you perceive a refracted image of the sky on the ground.
- This looks just like a reflection on the surface of a pool of water, which can easily cause confusion.