When visiting the Sahara Desert in North Africa, you will probably consider bringing plenty of water and sunscreen. But if you are planning to stay there at night, you better consider how you will keep yourself warm.
This is because temperatures in the desert can drop once the sun sets, from an average high of 38 degrees Celsius during the day to an average low of minus 4 degrees Celsius during the night, according to NASA.
“Incredible Earth” reveals answers to questions related to why this dramatic shift in temperature has occurred in arid deserts, how local animals and plants deal with such extreme wild phenomena, and more, on an exciting journey through everything you need to know about our world, and with photography Wonderful photography and insightful infographics along the way.
Heat and humidity:
The reason why arid deserts, the dry regions that cover about 35% of the land, become extremely hot, and therefore extremely cold, is a combination of two main factors: sand and humidity.
The sand does not retain heat well, so when the heat and sunlight hits the sandy desert in the daytime, the grains of sand in the upper layer of the desert absorb that heat and release it back into the air, according to a 2008 report from NASA’s Jet Propulsion Laboratory in Pasadena, California.
And during the day, the sand radiation from the energy of the sun and air greatly heats up and causes temperatures to rise. But at night, most of the heat in the sand is quickly released into the air and there is no sunlight to reheat it, making the sand and its surroundings cooler than before.
However, this phenomenon alone does not explain such a sharp drop in temperature, since when the sun sets on a tropical beach, you do not need to wear a winter coat.
The main reason for the sharp temperature change is that the desert air is very dry. In arid deserts such as the Sahara Desert and the Atacama Desert in Chile, the humidity, the amount of water vapor in the air, is nearly zero, and unlike sand, water has an enormous capacity to store heat.
Water vapor in the air traps heat near the ground like a giant invisible blanket and prevents it from dissipating into the atmosphere, according to the World Atlas.
Air with higher humidity also requires more energy to heat up, which means that it also takes longer to dissipate this energy and cool off the surrounding areas. Therefore, the lack of moisture in deserts allows these arid places to heat up quickly as well as cool down quickly.
Adapting to temperature extremes:
Despite these rapid temperature fluctuations, desert fauna adapts well to the extreme temperature changes in the desert.
“It tends to be a relatively small problem for them. The biggest challenge is getting enough food and water to survive,” said Del Denardo, an environmental physiologist at Arizona State University who specializes in desert fauna.
Reptiles are the most abundant and diverse animal group in the desert, and they adapt well to extreme temperature changes because they are cold-blooded or outside heat, which means that they do not need to invest energy in maintaining a constant body temperature.
In other words, reptiles could use this energy elsewhere, such as hunting. Many reptiles also benefit from being small, allowing them to find shaded corners during the day or warmer rocks at night.
However, large warm-blooded or endothermic mammals, such as camels, are too large to hide out of the sun and cannot let their body temperature drop. Instead, camels survive by maintaining a constant body temperature in both hot and cold conditions. It does so by having a lot of insulation in the form of fat and dense fur, Denardo said, which prevents it from gaining too much heat during the day and losing so much at night.
In contrast, desert birds use evaporative cooling, where they use water to transfer heat away from their bodies, such as how humans sweat and dogs gasp, by a group of different methods (some eagles urinate on their legs to cool off). But its ability to fly long distances between water sources or search for food, means you don’t have to worry about conserving water like other desert animals.
On the other hand, plants are more susceptible to extreme temperatures. Denardo indicated that it “faces a much greater challenge because it cannot move.” It is for this reason that famous desert plants, such as aloe vera, have evolved a range of defenses, such as thorns and poisons, to protect their precious waters from predators. However, freezing temperatures at night can be deadly to plants because the water freezes and expands within their tissues, which can cause irreparable damage. Therefore, plants only grow in areas where the air temperature does not drop below freezing for more than two hours every night, known as the freeze line.
– Climate change
Researchers are still discovering how climate change can affect arid places and living organisms, but “we will definitely see changes,” and Dinardo explained: “For most deserts, we expect an average temperature rise from 1.7 to 2.2 degrees Celsius.”
However, research indicates that “the nights will be much warmer,” according to Dinardo.
Instead, the real problem is that climate change may affect the amount of annual precipitation that desert organisms depend on, so that it will become less uniform, and there will be relatively wet years and relatively dry years. But despite the wet years, it only took a year of drought to cause major problems.
Source: Live Science