Butter is generally wrapped in wet cloth during summer if no refrigerator is available. ... As a result, water present in wet cloth readily evaporates. Since cooling is caused during evaporation, the temperature of butter gets lowered.

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Normally, butter melts due to heat in summers, unless stored in adequate coolness.

If refrigerator is not available in a household, butter is wrapped in a wet cloth to provide the required cooling.

When the water from the wet cloth evaporates, the butter wrapped inside becomes cooler and thus remains in solid state even during summers.