Clouds, Cumulus

CUMULUS CLOUDS ARE puffy and usually have well-defined boundaries. They form from the condensation or deposition of moisture in particles known as cloud nuclei present in the moist updrafts of convective plumes. The cloud particles can be composed of liquid water, supercooled water, or ice. These cloud particles are denser than air; therefore they increase the density of cumulus updrafts. However, water vapor is lighter than dry air, and therefore, except for the effects of the cloud particles, the moist updraft air is lighter than dry air at the same temperature and pressure. This effect of moisture on air density is known as virtual temperature. Scientists have shown that the virtual temperature effect is responsible for about 50 percent of the buoyancy of convective plumes ...