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Question
Why does a desert cooler cool better on a hot dry day?
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Solution
- When a liquid evaporates, its particles absorb energy from the surroundings to compensate for the loss of energy during evaporation. This makes the surroundings cool.
- In a desert cooler, the water inside evaporates. This absorbs energy from the surroundings, thereby cooling them.
- Again, we know that evaporation depends on the amount of water vapour present in the air (humidity). If the amount of water vapour present in the air is less, then evaporation is more. On a hot, dry day, the amount of water vapour present in the air is less.
- Thus, water present inside the desert cooler evaporates more, thereby cooling the surroundings more. That is why a desert cooler cools better on a hot dry day.
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