What conditions make a tornado likely to form??

Question

Please give as much detail as possible, AND LIST ANY SOURCES!!!!

Answer 1

Warm and hot air swirling around together

Answer 2

Tornadoes often develop from a class of thunderstorms known as supercells. Supercells contain mesocyclones, an area of organized rotation a few miles up in the atmosphere, usually 1–6 miles (2–10 km) across. Most intense tornadoes (EF3 to EF5 on the Enhanced Fujita Scale) develop from supercells. In addition to tornadoes, very heavy rain, frequent lightning, strong wind gusts, and hail are common in such storms.

Most tornadoes from supercells follow a recognizable life cycle.[15] That begins when increasing rainfall drags with it an area of quickly descending air known as the rear flank downdraft (RFD). This downdraft accelerates as it approaches the ground, and drags the supercell's rotating mesocyclone towards the ground with it.

Hope this helps.

Answer 3

different levels of storm

Answer 4

when hot and cold weather colide, it creates an unstable atmopshere

Answer 5

a tornado can be formed when hot and cold air front hit togethor and mix. I t can also be with different wind dirrections meeting. It then forms a funnel cloud (it looks like the clouds swirling in a circle together.) If the conditions stay right, the tornado grows and can even touch the ground. This is usally when it is most deadly. So these storms are very dangerous.

Answer 6

a f**t

Answer 7

Tornadoes are often formed by two air masses. One is often higher than the other. One is also usually warmer than the other well. When these two masses come in contact, they swirl and become a tornado.

Answer 8

A tornado is most likely to form when the upper air is moving in a direction, and the lower air is moving in the opposite direction. The temperature is above 50 degrees Fahrenheit.

Answer 9

For tornadoes to form you need instability, moisture, wind shear, high helicity, cold dry air aloft and warm moist air at the surface.  (To make this less confusing I will use the Plains as my example).

The reason why the mid-section of the US gets so many tornadoes is because the conditions that are needed usually all come together here.  Warm moist air advects Northward from the Gulf of Mexico.  Cool dry air advances Southward from Canada.  The warm moist air sits at the surface and the lower levels of the atmosphere (especially if winds are from the South or the Southeast) and in the mid and upper levels of the atmosphere temperatures are cold and the air is dry (winds coming from the North, or Northwest from Canada).  The warm and moist air at the surface helps to create instability (measured in Jules per kilogram, J/KG).  The more unstable the atmosphere the higher the chance for severe weather and tornadoes.  You can measure how unstable the atmosphere is by looking at Surfaced-Based Cape values (SBcape), Most-Unstable Cape (MUcape) values, Mixed-Layer Cape (MLcape) values, and Lifted-Index (LI) values.  During the spring and summer months you would like to see SBcape values at least 1000 J/KG , MUcape values of at least 1000 J/KG, MLcape values of at least 1000 J/KG and LI values of at least -4, however, these numbers are also dependent on how much shear is in place.  (This will be discussed later on).  

You also need lots of moisture at the surface and lower levels of the atmosphere.  The more moisture the better as this can also be an indication of an extremley unstable atmosphere and there is more juice for the storms to work with.  At the surface you would like to see dew points of at least 60F, however, tornadoes have also occurred with dew points as low as the 40's.  At 925mb (or about 1500FT from gornd level) you want dew points to be at least 20C ( 68F), at 850mb (or about 5000FT from ground level) you want dew points to be at least 12C (53.6F) and at 700mb (or about 10000Ft from ground level you want dew points to be at least 0C (32F).  This would indicate very moist air at the surface and lower levels of the atmosphere and dry air aloft.  

Temperatures can very but during the summer months you want surface temperatures to be at least 75F or higher.  The higher the temperatures the more unstable the atmosphere will be as well.  during the summer months you want 700mb temps to be below 10C.  Anything higher than 10C means temps aloft are quite warm and this creates a cap which can limit thunderstorm develpment or growth.  However, you do want a cap until at least early afternoon because if you don't have a cap thunderstorms will pop up all over the place and it would be really tough to get discrete activity.  500mb temps should be below -15C (5F).  This favors greter potential for hail and damaging winds as well.  

Now for shear.  You want directional shear and speed shear.  directional shear is change in wind direction with height.  You want a 45 degree angle in change from the surface up through 700mb.  In the Plains you want either S or SE winds at the surface with winds veering to about WSW at 700mb and more W at 500mb.  Speed shear is the change in wind speeds with height.  You would like to see about 20-30 knots at 925mb, at least 30-35 knots at 850mb, 40-45 knots at 700mb, at least 60 knots at 500mb and at least 85 knots at 250mb.  The more directional shear you have the higher the helicity values will be.  You would like to see helicity values of about 400 meters squared per second squared (m2s2), however, tornadoes can form with helcity valaues as low as 250 m2s2 but the chances are tornadoes would be short-lived.  

You also want cold temperatures aloft as stated before.  The better the change of temperature with height the more unstable the atmosphere is, the higher the lapse rate (decrease of temperature with elevation), and the greater the lift.    

The above mentioned parameters are parameters you look for during the summer months.  The parameters can vary depending on the season.  For example, during the fall and winter months you don't need as much instability as dynamics are usually stronger during these months.  

For soucrs you can use www.theweatherprediction.com or just even type tornadoes in google and you can find all sorts of sources.