During the day, the sand of the dunes of the Sahara is hot. You need good shoes, and cover yourself from head to toe, so as not to burn in the sun. But as soon as night falls, the temperature drops: sand is a very poor heat carrier, it quickly sends the energy accumulated during the day back into space. Details on this astonishing thermal amplitude.
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Desert thermal amplitude
If it is hot there during the day, the desert cools down cruelly at night. In winter, it can even freeze, the day-night thermal amplitude can easily exceed 20°C. The temperature drop nocturnal can be explained by two main factors: the heat capacity of the sand and the clouds.
The sand is composed of silicates which retain particularly badly the heat accumulated during the day. As soon as the sun has disappeared, each grain of sand isolates itself from the others, thus accelerating heat dissipation. In other words, the sandier the desert, the faster it losesenergy accumulated during the day. Moreover, the nights are clear, and the absence of water vapour in the air greatly inhibits the cloud formation. Without this natural barrier, all radiation infrared emitted by the ground is therefore sent directly to space. In a hot desert of the intertropical zone, the only heating is solar radiation.
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