Why does the temperature decrease in hot deserts to become very cold at night? How do living things adapt?

Arab weather - the deserts are characterized by a great contrast in temperatures between day and night, and this decrease in temperature may occur as soon as the sun sets, as the decrease can reach from an average of 38 degrees Celsius during the day, to an average low of -4 degrees Celsius at night, but why does this shift and the large temperature variance occur in arid deserts? How do the animals and plants there deal with such extreme natural phenomena?

Arid deserts are defined as dry areas that cover about 35% of the land on Earth, and these areas are characterized by becoming very hot and then turning to be very cold, and the reason is due to the combination of two main factors, namely: sand and humidity.

1 . Sand:

Sand does not retain heat. During the day when heat and sunlight hit the sandy desert, sand grains in the upper layer quickly absorb this energy and release it back into the air. Hot sand in the day releases a lot of heat into the air, which leads to a rise in temperature, At night, the surface sand layer has released most of the heat into the air, and there is no sunlight to reheat it, which makes the sand and the air around it cooler than before.

However, this phenomenon alone does not explain such a sharp drop in temperature during the night. On the tropical beaches there are sands that react in the same way from the heat of the sun, and despite that the temperature does not drop much when the sun goes down, so what explains the extreme cold at night?

2. Humidity:

The main reason for the sharp change in temperature is that the desert air is very dry, where the amount of moisture (the amount of water vapor in the air) is almost zero in arid deserts such as the Sahara Desert in Africa and the Atacama Desert in Chile, and unlike sand, water has a tremendous ability to heat storage.

Water vapor in the air traps heat near the ground like a giant blanket and prevents it from dissipating into the atmosphere, and air with higher humidity requires more energy to heat up, which means it takes longer to lose this energy, and therefore longer for areas to cool. surrounding it, so the lack of moisture in deserts allows arid places to heat up quickly and cool down quickly as well

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Organisms adapt to sharp variations in temperature

Despite these rapid temperature fluctuations in the desert, desert animals adapt well to these changes, and perhaps the biggest challenge is getting enough food and water to survive.

reptiles

Reptiles are the most abundant and diverse animal group in the desert, and they are well adapted to sharp changes in temperature because they are cold-blooded, which means that they do not need to invest energy in maintaining a constant body temperature, and this energy is used for something else (such as hunting ).

Many reptiles also benefit from being small in size, which allows them to find shaded corners during the day or take shelter on warmer rocks at night.

Mammals

However, there are large warm-blooded mammals (such as camels) that are too big to hide away from the sun, and cannot lower their body temperature. However, camels survive by maintaining a constant body temperature in both hot and cold conditions. By having a lot of insulation on their bodies (such as fat and dander), which prevents them from gaining too much heat during the day, or losing too much heat at night.

the birds

Desert birds use evaporation cooling, that is, they use the evaporation process of water to expel heat from their bodies, as happens in people sweating and dogs gasping , through a group of different ways, such as some eagles urinating on their legs to cool them, and birds do not suffer much in an environment The desert is like the rest of the animals, because it has the ability to fly long distances between water sources or to search for food.

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the plants

Plants are considered the most vulnerable creatures to the sharp change in temperature in the desert. They face a much greater challenge because they cannot move, which is why famous desert plants (such as cacti) have developed a range of defenses, such as needles and toxins , to protect their precious waters from predators.

However, freezing temperatures at night can be deadly for plants, because water freezes and expands within their tissues, which can cause fatal damage to them. Therefore, plants only grow in areas where the air temperature does not fall below freezing for more than two hours each night. , known as the freeze line.

The impact of climate change on deserts

Researchers are still figuring out how climate change can affect arid places and organisms, but we will definitely see changes, as an average temperature rise in deserts is expected between 1.7 and 2.2 degrees Celsius. However, research indicates that the nights will be warmer.

However, the real problem is that climate change may affect the amount of annual precipitation that desert organisms depend on, so that it becomes less uniform, and there will be relatively wet years and relatively dry years, but wet years will not be enough, as one year of drought is enough to cause In major problems in the ecosystem in the desert.

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