Clouds can go up to 60,000 feet (18288 m) high in the sky. These high-level clouds include cirrus, cirrocumulus, and cirrostratus that formed in the altitude range of 16,500 feet to 60,000 feet. The height of a cloud depends on various factors such as moisture content, ambient temperature and pressure, updraft winds, and dust particles in the atmosphere. As these factors vary with different locations, clouds are formed at different altitudes at different locations.
A typical cloud is made up of water droplets and ice crystals. This cloud composition usually varies with altitude and ambient conditions such as temperature and pressure. The high-level clouds such as cirrus, cirrostratus, and cirrocumulus are mostly made of ice crystals while low-level clouds such as cumulus, stratus are composed of water droplets. However, note that the low-level clouds can also be made up of water droplets and ice crystals if the ambient temperature drops below the frost point.
A typical cumulus cloud having a volume of 1 km3 can weigh approximately 3.3 million pounds (1525 tons). The weight of the clouds depends on the cloud liquid water content value and other factors such as temperature and pressure. Clouds at higher altitudes such as cirrus clouds have a lower mass than that of cumulonimbus clouds.
Clouds can float because clouds are made up of tiny micron size water droplets that can float similar to dust particles in the air. Due to tiny size, the water droplets and ice crystals have low terminal velocity and hence, they fall very slowly. The continuous warm updrafts in the atmosphere also force clouds upwards and keep them floating.
Clouds look white because the water droplets present in the clouds scatter visible light into all wavelengths equally. Due to identical scattering of all wavelengths, the sunlight remains white and clouds appear white.
Clouds are formed when the water vapors present in the air condenses and turn into water drops or ice crystals. The condensation of water vapors occurs on the tiny dust particles at an altitude where the temperature matches the dew point of the water.
High-level clouds such as cirrus clouds can move at a speed of more than 100 mph and can travel more than 2400 miles in a day. Clouds move due to wind and how fast a cloud can move is determined by the altitude at which they are formed. The wind speed increases with an increase in altitude. Therefore, high altitude clouds such as cirrus clouds move faster compared to low altitude clouds such as cumulus clouds.
Clouds look flat on the bottom because of the process of cloud formation. The condensation of rising moist hot air occurs only above a certain height or altitude called lifted condensation level (LCL). This level defines the flat base of the cloud. As more hot air rises from below, the base of the cloud remains the same while the existing clouds are forced upwards. Thus, this process causes clouds to have a flat bottom and a fluffy top.