The transfer of heat by the in the atmosphere as a result of caused by from below. A narrow between air masses that contrast in and/or . can be caused by air rising along either warm fronts or cold fronts. The most thunderstorms develop in cold fronts. A thunderstorm is a small . There are three stages to a thunderstorm are: , , . Severe weather is likely to occur during the stage of a thunderstorm. A thunderstorm that produces severe weather requires a very . help