Factors influencing the rate of liquid evaporation:

• Concentration of the substance evaporating in the air: If the air already has a high concentration of the substance evaporating, then the given substance will evaporate more slowly.
• Concentration of other substances in the air: If the air is already saturated with other substances, it can have a lower capacity for the substance evaporating.
• Flow rate of air: This is in part related to the concentration points above. If fresh air is moving over the substance all the time, then the concentration of the substance in the air is less likely to go up with time, thus encouraging faster evaporation. This is result of the boundary layer at the evaporation surface decreasing with flow velocity, decreasing the diffusion distance in the stagnant layer.
• Concentration of other substances in the liquid (impurities): If the liquid contains other substances, it will have a lower capacity for evaporation.
• Temperature of the substance: If the substance is hotter, then evaporation will be faster.
• Inter-molecular forces: The stronger the forces keeping the molecules together in the liquid state, the more energy one must get to escape.
• Surface area: A substance which has a larger surface area will evaporate faster as there are more surface molecules which are able to escape.
• Pressure: In an area of less pressure, evaporation happens faster because there is less exertion on the surface keeping the molecules from launching themselves.

Source: Wikipedia (All text is available under the terms of the GNU Free Documentation License)