Tornadoes

Tornadoes can form at any time of the year in any place susceptible to tornadoes. However, there is a "tornado season" in some countries when the vast majority of tornadoes occur. In the United States, most tornadoes occur between April and July, depending on the region of the country. In Canada, tornadoes tend to occur in June and July. In Australia, the tornadoes tend to occur from November to February, the warmer months in the southern hemisphere.

Tornadoes have been documented on every continent except Antarctica. Tornadoes tend to occur in the middle latitudes in both hemispheres, between 30° and 50°. These latitudes are regions where the warmer subtropical warm air meets the colder polar air, with different wind speeds and direction. These conditions can produce rotating air masses.

Scientists also do not fully understand how tornadoes lose energy and die. Scientists do know that similar air temperature and similar air pressure must exist throughout both the tornado and the whole storm system that caused the tornado in order for the tornado to die.

Scientists don’t fully understand exactly how tornadoes form, but the phenomenon has been heavily observed. When warm rising air (updraft) meets cooler sinking air (downdraft), and there is a change in wind direction and speed, a horizontal spinning effect can happen in a cumulonimbus cloud. If more updraft tilts the spinning air current from horizontal to vertical, a condensation funnel cloud (funnel-shaped cloud made of water droplets) may form.