Final answer:
The spinning motion cools the wet bulb thermometer in a sling psychrometer due to evaporation. Less humidity in the air increases the efficiency of evaporation, resulting in a greater cooling effect. Large temperature differences between the wet bulb and dry bulb thermometers are possible at higher temperatures due to the increased rate of evaporation.
Step-by-step explanation:
In a sling psychrometer, the wet bulb thermometer cools down when it is spun because of the process of evaporation. When the sling psychrometer is spun, water from the wet bulb thermometer evaporates, which requires energy and cools down the wet bulb thermometer. When there is less humidity in the air, the process of evaporation is more efficient, resulting in a greater cooling effect on the wet bulb thermometer.
Large differences in temperature between the wet bulb and dry bulb thermometers in a sling psychrometer are possible at higher temperatures because of the increase in the rate of evaporation. At higher temperatures, more water can evaporate from the wet bulb thermometer, leading to a larger temperature difference between the wet bulb and dry bulb thermometers.