Some of the most severe weather occurs when a cluster of thunderstorms affect an area for a prolonged period of time. Downburst Downburst is a term used to describe a small area of rapidly descending air beneath a thunderstorm. The strong winds can reach very high speeds causing significant damage along its path and is extremely dangerous to aviation. The action of rising and descending air within a thunderstorm cloud separates positive and negative charges. Lightning is the discharge produced when differences between ground and atmospheric electrical charges are large enough to overcome the insulating effect of the air.
Lightning can occur within cloud, cloud to cloud, and between cloud and ground.
Lightning often strikes outside of heavy rain and may occur as far as 10 miles away from any rainfall. Air near a lightning strike is heated to above 20,000 o C - hotter than the surface of the sun. Rapid heating and cooling of air near the lightning causes a shock wave that results in thunder. Lightning can damage electrical installations and induce fires. Most lightning deaths and injuries occur when people are caught outdoors.