Over recent weeks, severe storms have lashed the southeastern United States. The devastation has been enormous and the tragedy has been felt particularly harshly in Alabama, Mississippi, Tennessee, Georgia, Virginia, Kentucky and now Oaklahoma.
The recent tornadoes are some of the fiercest experienced in the US for 40 years and some have been classified as EF5, which is the strongest tornado category.
A combination of cold air sitting across North America, meeting warm, moist air rising up from the Gulf of Mexico has helped to create these deadly conditions. As the warm air rises above the colder air, it begins to spiral up into the upper atmosphere. The Jet Stream is also hovering close to both of these air masses, which encourages more spiraling and helps to create super cells, which form into the strongest of all tornadoes.
Here are some facts about Tornadoes:
- Tornadoes can occur all over the world but they are most commonly found in the United States
- Tornadoes usually cause around 1500 fatalities per year
- The strongest tornadoes have rotating winds that can reach speeds of up to 250 mph
- The base of a tornado can measure over a mile wide but it can stay on the ground and travel for over 50 miles
- It’s the dust and debris that allows the tornado to be seen, as the winds themselves are invisible. Sometimes a cloud can form within the funnel
- Tornadoes can move in any direction but they tend to move from a southwesterly to a northeasterly direction
- While tornadoes can be stationary, the average forward speed of a tornado is 30 mph. They can reach forward speeds of up to 70 mph
- Waterspouts are formed when tornadoes are formed over warm water. They can then move onshore and cause coastal damage
As tornadoes rip through an area, hailstorms are often a side effect. Why does it hail? The storm causes large air currents, called updrafts, to rise. As they rise the air currents take with them droplets of moisture, which eventually freeze when they get high enough where temperatures aare colder. Once the droplets have frozen, they become heavier and fall back to the ground because the updraft can’t support them any longer...gravity! Large hailstones can actually fall at a rate of 100 mph!
Of course, thunderstorms also have lightening and this causes it’s own set of problems. When lightening strikes, the air nearby is heated to 50,000 °F, which is hotter than the surface of the sun. The risk of an outbreak of fire is obviously a huge one. As the air around lightening rapidly heats and cools down it causes a shock wave that we hear as thunder.
The National Oceanic & Atmospheric Administration runs a Storm Prediction Center at www.spc.noaa.gov where you can access all their latest reports and information.