A desert cooler cools better on a hot dry day because on a hot dry day temperature is high and humidity is less which helps in better evaporation. Due to the higher rate of evaporation it gives better cooling effect.

On a hot dry day the temperature is high and humidity is low.A desert cooler functions on the principle of evaporation.The water takes heat from the hot desert cooler and evaporates .The evaporation of water cools pad and circulating fan. as a result , the incoming air is also cooled down.

Introduction:

A desert cooler, also known as an evaporative cooler, is a device that cools the air by evaporating water. It is commonly used in dry and hot regions to provide relief from the scorching heat. Unlike traditional air conditioners that use refrigerants to cool the air, desert coolers work on the principle of evaporation, making them more suitable for hot and dry climates.

Explanation:

1. Evaporative Cooling:
Desert coolers operate on the principle of evaporative cooling. When hot and dry air passes through the cooling pads, water from the pads evaporates, absorbing the heat from the air. This process cools the air, which is then blown into the room by a fan. The evaporation of water provides a natural and energy-efficient way to cool the air.

2. Dry Air and Evaporation:
One of the key factors that make a desert cooler more effective on a hot dry day is the low humidity level. In hot and dry weather, the air has a low moisture content, which allows for faster evaporation. Dry air has the capacity to absorb more water vapor, enhancing the cooling effect of the desert cooler.

3. Latent Heat of Vaporization:
Evaporation is an endothermic process, meaning it requires heat energy to occur. When water molecules evaporate, they take away heat from the surrounding air, resulting in a drop in temperature. This phenomenon is known as the latent heat of vaporization. In a desert cooler, the water absorbs heat from the hot air, reducing its temperature and making it feel cooler.

4. Increased Cooling Efficiency:
On a hot dry day, a desert cooler can cool the air more efficiently due to the low humidity level. Since the air is already dry, it has a higher capacity to absorb moisture. As a result, the evaporation process is faster, leading to a greater cooling effect. Additionally, the dry air allows for better evaporation from the cooling pads, maximizing the cooling potential of the desert cooler.

Conclusion:

In conclusion, a desert cooler cools better on a hot dry day due to the low humidity level and the increased efficiency of the evaporation process. The dry air allows for faster evaporation, resulting in a significant drop in temperature. This makes desert coolers an ideal choice for hot and dry climates, providing effective and energy-efficient cooling without the use of refrigerants.