How do tornadoes form facts?
Tornadoes form where warm moist air is trapped underneath a layer of cold, dry air. This instability is upset when the warm bottom layer gets pushed up — either by heating near the ground, or by an influx of cold air. As the moist air rises, it cools, forming clouds and thunderstorms.
Most tornadoes form from thunderstorms. You need warm, moist air from the Gulf of Mexico and cool, dry air from Canada. When these two air masses meet, they create instability in the atmosphere. Most strong and violent tornadoes form within this area of strong rotation.
- In this area, known as Tornado Alley, storms are caused when dry cold air moving south from Canada meets warm moist air traveling north from the Gulf of Mexico. Tornadoes can form at any time of year, but most occur in the spring and summer months along with thunderstorms.
- Tornado paths range from 100 yards to 2.6 miles wide and are rarely more than 15 miles long. They can last from several seconds to more than an hour, however, most don't exceed 10 minutes.
- Hurricanes begin as tropical storms over the warm moist waters of the Atlantic and Pacific Oceans near the equator. (Near the Phillippines and the China Sea, hurricanes are called typhoons.) As the moisture evaporates it rises until enormous amounts of heated moist air are twisted high in the atmosphere.
The intense spinning of a tornado is partly the result of the updrafts and downdrafts in the thunderstorm (caused by the unstable air) interacting with the wind shear, resulting in a tilting of the wind shear to form an upright tornado vortex.
- Tornado Season. Tornadoes can occur at any time of the year. In southern states, peak tornado occurrence is March through May, while peak months in northern states are during the summer. Tornadoes are most likely between 3 and 9 p.m. but have occurred at all hours.
- Tornadoes that form on land can cross bodies of water, including rivers and lakes. Tornadoes can also form on water. These tornadoes are called “waterspouts.” Never think that a body of water will protect you from a tornado.
- During a tornado
- Go to the basement or take shelter in a small interior ground floor room such as a bathroom, closet or hallway.
- If you have no basement, protect yourself by taking shelter under a heavy table or desk.
- In all cases, stay away from windows, outside walls and doors.
They are usually the extreme result of a supercell thunderstorm. During the storm cold air and warm air combine in a set pattern: the cold air drops as the warm air rises. The warm air eventually twists into a spiral and forms the funnel cloud that we all associate with a tornado.
- They are usually the extreme result of a supercell thunderstorm. During the storm cold air and warm air combine in a set pattern: the cold air drops as the warm air rises. The warm air eventually twists into a spiral and forms the funnel cloud that we all associate with a tornado.
- F3. F4. F5. The Fujita scale (F-Scale), or Fujita–Pearson scale (FPP scale), is a scale for rating tornado intensity, based primarily on the damage tornadoes inflict on human-built structures and vegetation.
- Tornadoes are most common in the central part of the United States, known as the Great Plains. This area is suited to bring all of the ingredients together to forms tornadoes. More than 500 tornadoes typically occur in this area every year and is why it is commonly known as "Tornado Alley."
Updated: 21st September 2018