New Delhi, June 19 -- Air coolers are often promoted as a cheaper alternative to air conditioners, but their performance depends heavily on the weather. If you live in a city where the air already feels damp, an air cooler may not deliver the same relief it does in dry regions. That is because air coolers rely on evaporation to reduce temperature, and high humidity limits how much evaporation can take place.

When moisture levels in the air are low, coolers work efficiently by passing hot air through water-soaked cooling pads. In humid conditions, however, the air struggles to absorb additional moisture. The result is weaker cooling and a room that may feel more humid than comfortable.

That said, air coolers are not completely ineffectiv...