How long does it take for a cup of room temperature water to evaporate in the sun?

There are other factors to consider. Outside temperature. If you are at the artic in below zero weather the water would freeze before if evaporates. Altitude. Higher altitude on a mountain gives a lower boiling point, ant at the same temperature, would evaporate faster. Humidity. High humidity will slow the rate of evaporation.

Size of the cup. A measuring cup is 8 ounces. A tea cup is less, recent cup sizes for coffee have increased to ridiculous size.