Moisture in the air typically comes from the oceans—and areas near warm ocean currents evaporate lots of moisture into the air. This lift usually comes from differences in air density. Warmer, less dense air rises upward, creating lift.
As the air lifts higher and higher, it causes a storm cloud to grow taller and taller. Right now, at this very moment, there are about two thousand thunderstorms going on around the world.
Even though thunderstorms are common, they are still dramatic events with intense rain, hail, wind, lightning, thunder, and even tornadoes. Thunderstorms form when warm, moist air rises into cold air. The warm air becomes cooler, which causes moisture, called water vapor, to form small water droplets - a process called condensation. The cooled air drops lower in the atmosphere, warms and rises again.
As more water vapour condenses out inside the cloud, the water droplets merge and grow, while ice particles also form and combine in the freezing, upper reaches of the cloud. Once the water droplets and ice particles are heavy enough, they begin to fall as rain or hail. In their wake, they generate a current of cold air rushing downward, spreading out and causing strong winds at ground level, as well as a drop in temperature.
Strong up to more than mph straight-line winds associated with thunderstorms knock down trees, power lines and mobile homes. Tornadoes with winds up to about mph can destroy all but the best-built man-made structures. Where are severe thunderstorms most common? The greatest severe weather threat in the U. But, no place in the United States is completely safe from the threat of severe weather.
A watch can cover parts of a state or several states. Warnings mean there is a serious threat to life and property to those in the path of the storm. ACT now to find safe shelter!
A warning can cover parts of counties or several counties in the path of danger. How does a thunderstorm form? As the air rises, it transfers heat from the surface of the earth to the upper levels of the atmosphere the process of convection.
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