In the 1962 Hollywood movie Lawrence of Arabia, the film's hero, a British lieutenant, travels for a few days through the vast deserts, but he does not know whether he will reach his destination or will be lost and die in the seemingly without desert End.
You will notice that when the hero of the film rests at night under the starlit sky, he covers himself well with a heavy blanket. You may have wondered, "Why does he have a blanket? Aren't deserts supposed to be very hot?"
Deserts are notoriously hot during the day, but not many people realize that they suddenly turn cold at night.
Perhaps this reminds us a little of Mercury, the closest planet to the sun, whose temperature at night drops to -170 degrees Celsius, while it reaches 450 degrees Celsius during the day, due to the fact that Mercury is not surrounded by an atmosphere and then when the sun sets, there is nothing on its surface to keep with heat.
Temperatures in the desert drop by an average of 42 degrees Celsius overnight (communication sites)
But why does this happen in the desert?
With the difference, of course, why might temperatures in the desert drop by an average of 42 degrees Celsius overnight?
According to NASA, once the sun sets, the temperature may drop from an average high of 38 degrees Celsius in the day to an average low of -4 degrees Celsius at night.
According to Live Science, this is due to a combination of two main factors, namely sand and moisture.
Sand warms the air
Sand is an interesting material;
It is dry, but slippery, and its particles are larger than other types of soil, and this is the main reason why it does not absorb water well, as well as it does not retain heat well either, and then when the heat and sunlight hit the sandy desert, the sand grains in the upper layer of the desert absorb That heat is then released back into the air by radiation, and the desert sands here act as a mirror and heat the air above the ground.
You will notice that other types of terrain, such as forests, beaches, plains, and mountains, are not as hot as deserts because they do not radiate all their heat into the air above their surface, while deserts certainly do.
But if sand is the main reason why deserts are so hot during the day, what makes them cold at night?
In some arid deserts such as the Sahara Desert and the Atacama Desert, humidity is almost zero degrees (Getty Images)
Desert air and humidity
The main reason for the sharp change in temperature at night in the desert is that the desert air is so dry, that in some arid deserts such as the Sahara and the Atacama Desert in Chile, the humidity is almost zero degrees.
Unlike sand, water has a tremendous capacity to store heat, so the water vapor in the air traps the heat near the ground like an invisible giant blanket and prevents it from dissipating into the atmosphere.
In normal terrain, when the sun warms the Earth, it absorbs a lot of heat.
At night, when the sun goes down from the sky, the earth radiates some of the heat it has stored in the day, and that heat is captured by the water content or moisture in the air above the ground, since the air is moist in those places.
In the desert, when the sun sets and the sand begins to lose its heat through radiation, the air above the ground cannot retain or stop this heat, because this air is not humid;
This is why this heat is lost so quickly, which leads to a significant drop in temperature during the night.
Moreover, deserts do not have much cloud cover, and this makes it more difficult to retain heat above the Earth's surface, and then the Earth's heat escapes, leaving behind an unforgiving cold.
The coldness of deserts at night has a lot to do with humidity, clouds and even wind, but contrary to popular belief, not all deserts lack moisture.
Places like Kuwait and the United Arab Emirates in the Arabian Peninsula are more humid than other deserts, so these deserts do not get cold at night, because their moist air retains some of the heat radiated by the earth.
Antarctica is technically a desert (Ca' Foscari University)
How can Antarctica be a desert?
When you think of the word "desert," the first thing that often comes to mind is the endless expanse of land covered in sand, but did you know that the Arctic, completely covered in snow, is actually a desert?
The lack of precipitation or other forms of precipitation such as snow and frost is what characterizes the desert;
Most deserts receive less than 300 mm annually compared to rainforests which receive more than 2,000 mm.
Therefore, Antarctica, which is covered in ice and has a minimum temperature of less than -75 degrees Celsius, is technically a desert;
There is very little snow and rain throughout the year, making it one of the largest and driest deserts on the planet.
Some deserts, such as the Atacama Desert in South America, have no rain at all (Getty Images)
Why does rain not fall at all over some deserts?
Most deserts get little rain each year, but some deserts, such as the Atacama Desert in South America, get no rain at all.
Why does this happen?
And what locations and conditions can create a desert?
Deserts are found on almost every continent, and they cover 35% of the Earth's area, and are mainly found around 30 to 50 degree latitudes, called mid-latitudes, and these areas are located roughly halfway between the equator and the North and South poles.
One of the main things that affect the location of deserts is the physical property of air, that it can hold more water when it's warmer.
Because hot, moist air always rises from the equator;
As warm air continues to rise from the equator, it pushes cold air away;
The cold air moves north and south before falling back toward the Earth by about 30 to 50 degrees north and south from the equator.
When the cold air begins to retreat toward the ground or descend, at 30 to 50 degrees north and south of the equator, this falling air makes the dry air drier, and it turns the land below into a desert.