What kind of atmospheric conditions do you need for severe storms to develop?

Question

What kind of atmospheric conditions do you need for severe storms to develop?

Answer 1

I hope ,by severe storm you mean tropical revolving storms like hurricanes, typhoons, cyclones etc.In that case,the following are the conditions required.

A warm surface water surface(atleast 26.5 degree celcius),sufficient moisture in the atmosphere upto 500 mb level(about 5 Kms) with steep lapse rate,away from the equator(atleast 500 Kms),already existing ground-level disturbance and weak vertical wind shear are the minimum required conditions.

Answer 2

Severe storms develop when cold and warm air collides; normally along cold fronts, but occasionally along a warm front.  The warm air can carry a lot of moisture, but when it collides with the cold air it is cooled and forced to drop that moisture.  This can create different air pressure, it can form clouds and it can form air circulation as well as fall to the earth as precipitation.

The cold air cuts underneath the moist warm air forcing it to drop its water.  This action also causes vertical rotation in the air.  If that rotation becomes horizontal to the ground then a tornado or hurricane can form.

Thunderstorms are huge piles of cloud with air movement high into the atmosphere.  The water vapor in that rising warm air freezes and drops out.  It can thaw and fall as rain, or build up to fall as hail, or fall as snow.  The loss of moisture to the cloud creates energy which is what charges a thunderstorm up.  That energy can be expressed in wind energy so hurricanes gain strength with a warm water source.  Tornados are usually spawned from thunderstorms where the vertical air rotation slips and becomes horizontal.  It can form a violent funnel cloud that can extend to the ground moving across the ground as the clouds move across the sky.

A tornado needs violently moving air and when the warm air from the Gulf of Mexico reaches the cold arctic air from Canada in the Middle of the US we have an area called tornado alley.  Tornados can also be spawned by hurricanes.

A hurricane starts as a dust storm in the Sahara Desert going west; it strengthens as it gathers moisture and forms a low pressure center with a rotating exterior.  It gains power from the rising warm air that drops its moisture and so they lose power when they make landfall.  Tropical storms that form cyclones can start in the US or Australia turning as small storms that gain strength as they cross the Pacific Ocean.

According to Wikipedia:  http://en.wikipedia.org/wiki/Thunderstor...

"A thunderstorm, also called an electrical storm or lightning storm, is a form of weather characterized by the presence of lightning and its attendant thunder.

Warm air is less concentrated than cool air, so warm air rises within cooler air, similar to hot air balloons. Clouds form as warm air carrying moisture rises within cooler air. As the warm air rises, it cools. The moist water vapour begins to condense. When the moisture condenses, this releases energy that keeps the air warmer than its surroundings, so that it continues to rise. If enough instability is present in the atmosphere, this process will continue long enough for cumulonimbus clouds to form, which support lightning and thunder.

All thunderstorms, regardless of type, go through three stages: the cumulus stage, the mature stage, and the dissipation stage. Depending on the conditions present in the atmosphere, these three stages can take anywhere from 20 minutes to several hours to occur."

According to Wikipedia:  http://en.wikipedia.org/wiki/Tornado

"A tornado is a violently rotating column of air which is in contact with both the surface of the earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. Tornadoes come in many sizes but are typically in the form of a visible condensation funnel, whose narrow end touches the earth and is often encircled by a cloud of debris.

Most tornadoes have wind speeds between 40 mph (64 km/h) and 110 mph (177 km/h), are approximately 250 feet (75 m) across, and travel a few miles (several kilometers) before dissipating. Some attain wind speeds of more than 300 mph (480 km/h), stretch more than a mile (1.6 km) across, and stay on the ground for dozens of miles (more than 100 km)."

According to Wikipedia:  http://en.wikipedia.org/wiki/Hurricane

"A tropical cyclone is a storm system characterized by a low pressure center and numerous thunderstorms that produce strong winds and flooding rain. A tropical cyclone feeds on heat released when moist air rises, resulting in condensation of water vapour contained in the moist air. They are fueled by a different heat mechanism than other cyclonic windstorms such as nor'easters, European windstorms, and polar lows, leading to their classification as "warm core" storm systems.

The term "tropical" refers to both the geographic origin of these systems, which form almost exclusively in tropical regions of the globe, and their formation in Maritime Tropical air masses. The term "cyclone" refers to such storms' cyclonic nature, with counterclockwise rotation in the Northern Hemisphere and clockwise rotation in the Southern Hemisphere. Depending on their location and strength, tropical cyclones are referred to by other names, such as hurricane, typhoon, tropical storm, cyclonic storm, tropical depression and simply cyclone."