Studies from the Earth show that the clouds on Venus are primarily composed of droplets of sulfuric acid, with water droplets mixed in, Sulfuric acid mays sound strange as a cloud constituent, but the Earth too has a significant layer of sulfuric acid droplets in its stratosphere. However,the water in the lower layers of the Earth' atmosphere,circulating because of weather,washes the sulfur compounds out of these layers, whereas Venus has sulfur compounds in lower layers of its atmosphere in addition to those in its clouds.