Energy from the sun travels through space as solar radiation. Earth's surface absorbs this radiation, and conducts heat energy to the overlying air. Absorption and conduction are not uniform across variations in earth's surface, leading to [[Heat Imbalances]] and local areas of relatively warmer and cooler air. All other factors being the same, warmer air is less dense than cooler air; the warmer air becomes buoyant and tends to rise. The process of transferring heat energy within a fluid is known as convection, and the rising mass of air is called a thermal. ![[AWH thermal.png]]