Isolated tornadoes are a type of severe thunderstorm that produces winds with a swath of destruction. This swath of damage is often very extensive and includes everything from cars to brick buildings.
The reason for the destruction is that a tornado has wind speeds much higher than hurricane-force winds. These high-speed winds can tear apart trees and shatter windows in skyscrapers.
Tornadoes form when cold air from the upper atmosphere clashes with warm, moist air near ground level. This clash of temperatures, along with other factors such as wind shear, creates instability in the thunderstorm.
In addition, a powerful updraft is created in a tornado. This updraft rotates horizontally and draws moisture from the lower atmospheric layer into it.
This causes the cloud to form a funnel or other shape. The funnel is an indication that a tornado has formed.
Another sign that a tornado may be developing is the formation of wall clouds. These clouds typically form near the downdraft/updraft interface, a region where rain-cooled air is pulled into the updraft by a strong thunderstorm.
Large hail is also a common occurrence during tornadoes. The most powerful thunderstorms often produce hail larger than golf balls.
Generally, tornadoes are most likely to develop in late spring and early fall when temperatures and humidity merge as the seasons change. However, some tornadoes can form during any month of the year if conditions are right.
