Meterology unit 4

Thunderstorm

a rain bearing cloud that also produces lightning that may also produce gusty winds, heavy precipitation, hail, an/or tornados

What conditions do there have to be to form thunderstorms

warm, moist, unstable, or conditionally unstable air, along with some form of lifting.

what are the 3 classifications of thunderstorms

Severe, ordinary cell, and other thunderstorms

severe thunderstorms

winds more than 58mph and/or 1 inch or more diameter of hail and/or may spawn a tornado

Ordinary cell thunderstomr

a small self extinguishing multicellular thunderstorm that is frequently associated with the mT from the Gulf of Mexico. They are often 2 miles wide or smaller, form in the midafternoon that last for a hour

what are the 3 stages of a ordinary cell thunderstorm

Cumulus, mature, and dissipating

what is the cumulus stage of a ordinary cell thunderstorm

warm moist air is heated by the ground causing parcels of air to rise (updrafts). air then reaches the lifting condensation level and clouds form and continue to grow as long as updrafts continue and there is still moist air in the atmosphere.

what is the mature stage of a ordinary cell tunderstorm

the clouds reach a high enough altitude that precipitation begins to occur along with heavy rain fall that creates cold downdrafts. These are oriented next to the warm updrafts

what is the dissipating stage of a ordinary cell thunderstorm

the downdrafts start to block the updrafts and the storm loses it source of energy and beings to evaporate

what are some examples of other thunderstorms

squall lines, mesoscale convective complexes (MCC), and supercell thunderstorms

Anvil

the top of a storm that is held by the tropopause. The storm moves in the way that the anvil is going

Overshooting top

up drafts punch through the stratosphere

out flow boundary/gust front

when cold downdrafts hit the ground and spread out causing warm updrafts that prolong the storm or create new cells.

shelf cloud

the bottom of the cloud that peaks out due to the gust front

roll clouds

Horizontal vortex that is generally out in front of a thunderstorm. Formed by warm updrafts and cold downdrafts passing each other

Mammatus clouds

Bumpy clouds under the anvil formed by pockets of cold moist air being pushed down into dry air.

doppler radar

radio detection and ranging

reflectivity

the strength of the energy that is returned to the radar after it bounces off precipitation targets. the stronger the returned energy the heavier precipitation

Velocity

The faze or doppler shift of the returned energy. Red means moving away from radar and green means moving toward

Dual polarization

An upgrade that sends out a vertical beam along with the horizontal beam. allows for identification of rain, hail, the rain/ snow line, and ice pellets along with debris balls.

other thunderstorms

sometimes called self propagating storms and include a titled storm axis due to strong wind shear

wind shear

Relatively abrupt changes in wind speed and or direction with increasing height

squall lines

a narrow ban of thunderstorms cells typically associated with a cold front or dry line, individual storm outflows merge to produce a continuous, well developed gust front.wh

what are the characteristics of a squall line

occurs near the front or many miles ahead of the front and is often over 300 miles long but only a few miles wide. may last 10 hours or more and typically produces heavy rainfall, strong straight-line winds(58 mph or more), and hail.

Mesoscale convective complexes (MCC)

A slow moving oval cluster of thunderstorm cells that is typically 100s of miles across and can last over 12 hours

What forms a Mesoscale convective complex

Requires region inflow of warm moist air. Gust fronts form existing cells create new thunderstorms. These storms produce most of the growing season rainfall

Supercell thunderstorms

a single powerful storm cell with a core of rotation that is typically 12 to 30 miles wide and has a prominent anvil and overshooting tops

what forms supercell thunderstorms

require strong wind shear and include a core of intense rotating updrafts called mesocyclone. Responsible for most the violent tornadoes

Lightning

a current of electricity between a cloud and the ground that can heat up to 54,000 degree F and also causes thunder

what are the steps to lightning

separation of charge + stepped leader + streamer + stroke + dart leader + stroke

separation of charge