It rained last night and today everything looks greener than yesterday. The rain gauge in my backyard registered 0.25 inches. This amount of rain is not substantial enough to reach the root zone. So don't stop watering yet. However, it is sufficient to wash off the dust that have accumulated on the leaves allowing the leaves to get high definition radiation from the sun. It is also enough to cause a dramatic change in the humidity in the immediate surroundings of the plant (microclimate). An increase in humidity results in a decreased rate of transpiration. Transpiration is water loss through the leaves. As a result, more of the water available to the plant (within the root zone) will be used for photosynthesis instead of being transpired.