"Thermal" pertains to the dynamics of heat and temperature. In a meteorological context, a thermal is a column of rising air in the Earth's lower atmosphere, caused by the uneven heating of the Earth's surface by solar radiation. This process is an example of convection, specifically atmospheric convection. Thermals are instrumental in creating cumulus clouds as the rising, cooling air condenses water vapor into visible droplets. The properties of the troposphere greatly influence the size and strength of thermals. Thermals also serve as a significant source of lift for soaring birds and gliders. In the solar context, thermals form hexagonal prisms known as Bénard cells.