Deserts are renowned for their scorching daytime temperatures, but what often surprises travelers is the dramatic drop in temperature once the sun sets. Have you ever wondered why deserts get so cold at night?
In this article, we embark on a journey to uncover the secrets behind the nocturnal chills of arid landscapes. We’ll delve into the science of desert climates, the role of clear skies, and the unique conditions that make desert nights exceptionally cold.
Join us as we demystify this intriguing phenomenon and gain a deeper understanding of the desert’s day-night temperature extremes.
Sand Heats the Air Above it
Sand is a fascinating material. It’s dry but slick, and it doesn’t absorb water well since its particles are larger than those in other soil types.
Deserts are so hot because sand is poor at insulating against the sun’s rays.
In deserts, the sand doesn’t retain the sun’s warmth when it’s heated by the sun. Instead, it reflects the sun’s rays and warms the air above the ground.
Forests, beaches, plains, and mountains don’t radiate as much heat to the air above their surfaces as deserts do, thus they don’t get as hot.
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Why Are Deserts So Hot During the Day and Cold at Night?
The dramatic shift in temperature that occurs between the day and night in a desert is one of nature’s most striking extremes.
Human occupants might be subjected to agonising pain at scorching temperatures. After dark, though, the situation flips, and a warm coat could be handy.
The Sahara Desert in Africa experiences extreme diurnal temperature swings, with daytime highs of 100 °F and nighttime lows of 25 °F on average. Why does this happen?
Blame the Sand
Sand is a good heat sink, allowing the sun’s rays to be reflected back into the atmosphere. However, it is poor at keeping heat inside. When the sun goes down, the sand quickly gives up its stored heat.
Humidity is the one thing that could keep warm air in the desert overnight, but there isn’t much of it. Heat is retained by the air due to the presence of water vapour.
It’s similar to a blanket in that it traps air inside, making it difficult for temperature to change. The vapour will keep the heat for a long time after the heat source is turned off. The desert will rapidly cool without the sun or humidity to trap the day’s heat.
Deserts, despite having the same average temperature as other regions, may feel much warmer due to the higher humidity levels. Compared to a dry climate, which makes direct use of the sun’s heat, water vapour requires a great deal of energy to heat up.
The Desert Environment
Deserts are characterized by their harsh, arid climates with limited vegetation cover. During the day, the sun’s rays beat down relentlessly on the desert landscape, causing the surface temperature to soar to scorching levels. However, as evening approaches, a stark transformation occurs.
Clear Skies and Radiational Cooling
One of the primary reasons deserts get cold at night is the absence of cloud cover. Deserts typically have clear skies throughout the day, allowing the Earth’s surface to radiate heat rapidly after sunset. This process is known as radiational cooling.
Radiational cooling occurs when the ground, which has absorbed heat throughout the day, loses that heat quickly by emitting it as infrared radiation into the clear night sky.
In areas with ample moisture and cloud cover, some of this radiated heat is trapped by greenhouse gases, preventing a drastic drop in temperature. However, deserts lack the moisture and cloud cover needed to retain heat effectively.
Low Humidity and Dry Air
Another critical factor contributing to the extreme cooling of deserts at night is their low humidity levels. Deserts are notorious for their dry, arid conditions, which means there is very little moisture in the air.
Unlike more humid regions, where water vapor in the atmosphere can act as a thermal blanket, deserts have dry air that can’t trap heat effectively.
In a humid environment, moisture in the air can absorb and re-radiate heat, acting as a buffer against temperature extremes.
However, in deserts, the absence of moisture prevents this moderating effect. As a result, the heat absorbed during the day escapes rapidly into the clear night sky, causing temperatures to plummet.
Local Geography and Elevation
It’s essential to note that not all deserts experience the same level of nighttime cooling. The local geography and elevation of a desert play a significant role in determining the extent of temperature drops.
For instance, desert regions with significant elevation, such as high desert plateaus, may experience even colder nights due to their proximity to the upper atmosphere.
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Conclusion
Extreme heat is generated during the day because the sand absorbs and radiates the sun’s rays, causing the air around it to become extremely hot. However, when the sun goes down, the temperature drops dramatically and the sand’s heat quickly radiates into the air.
According to an article published in Science Times, extreme temperature swings in deserts can be attributed to the lack of moisture in the air. The Science Times explains that deserts like the Atacama and Sahara have almost no humidity because water vapour has a greater capacity to trap heat than sand.