If you visit the Sahara desert during the day it is essential that you bring plenty of water and sunscreen. However, if you also plan to spend the night you should bring a coat or a sleeping bag. The reason? The temperature in the Sahara can plummet after sunset, from 40 degrees Celsius during the day to about two or three degrees below zero at night , according to NASA data. But, do you know why this drastic change in temperature occurs in deserts like the Sahara or Atacama?
Heat and humidity, key factors
The variation in the temperature of deserts is due to two main factors: sand and humidity. Sand does not retain heat very well. So when the sun hits the desert, the sand in the top layer absorbs and also releases heat into the air. During the day, radiation from the sand overheats the air and causes the temperature to rise.
However, at night, most of the heat from the sand quickly radiates into the air. And, since there is no sunlight that overheats the environment, the sand and the surroundings are colder than before, thus lowering the temperature. However, this phenomenon alone does not explain such a drastic drop in thermometers.
In arid deserts like the Sahara, humidity is practically non-existent. Also, unlike sand, water retains heat very well. A humid environment requires more energy to heat up, which means that it takes more time for that energy to dissipate and the environment to cool down. Therefore, the lack of humidity in deserts allows arid areas to warm up quickly, but to cool down at the same rate.
Extreme temperatures
Despite the extreme temperatures, desert animals are used to surviving in this habitat. In fact, the biggest challenge for these animals is getting enough food and water to survive. Reptiles (the most abundant group of animals in the desert) are used to variations, as they are cold-blooded. Therefore, they need that heat to maintain their body temperature.
Other reptiles benefit from being small, looking for shady spots during the day or warmer rocks at night. However, warm-blooded mammals (such as camels) are too large to hide from the sun and cannot allow their body temperature to drop. Therefore, these animals survive by maintaining a constant body temperature in hot and cold conditions.
