Why does rain sometimes evaporate before reaching the ground in a desert?

In desert environments, rain sometimes evaporates before it reaches the ground due to the extremely low relative humidity of the air beneath the clouds.12

Because deserts are characterized by a significant shortage of moisture, the air is often far below water vapour saturation levels. When rain falls from a cloud into this dry, unsaturated air, the rate of evaporation can exceed the rate at which the precipitation falls. This process is further encouraged by the high daytime temperatures common in many desert regions, which increase the air's capacity to hold water vapour and accelerate the transition of falling droplets back into a gaseous state.12