Term
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Definition
a CLOUD that produces THUNDER, LIGHTNING, HEAVY RAIN and SOMETIMES HAIL and TORNADOES
-average 14,000 thunderstorms a day |
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Term
| What is thunderstorm DISTRIBUTION worldwide? |
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Definition
MOST storms develop in EQUATORIAL REGIONS
-in US: MOST develop in SOUTHEASTERN REGIONS, like FLORIDA. |
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Term
| What are the TYPES of THUNDERSTORMS? |
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Definition
| There are ORDINARY-CELL THUNDERSTORMS and SEVERE THUNDERSTORMS in which include MULTI-CELL THUNDERSTORMS and SUPER-CELL THUNDERSTORMS |
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Term
| What is an ORDINARY CELL THUNDERSTORM? |
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Definition
-These are WIDELY SCATTERED STORMS
-They develop in SUMMER in MIDDLE LATITUDES IN US.
-They are usually SHORT-LIVED storms |
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Term
| What is a SEVERE THUNDERSTORM? |
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Definition
These are storms that are capable of producing:
1. heavy showers
2. flash floods
3. hailstones
4. tornadoes
5. strong/gusty surface winds (over 58mph)
-they DEVELOP on COLD FRONTS
-UPDRAFTS, DOWNDRAFTS and GUST FRONTS |
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Term
| What is SUPER-CELL THUNDERSTORM? |
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Definition
-They are storms that are SINGLE CELL THUNDERSTORMS
-storms that have ROTATING UPDRAFTS
-they CAN produce DAMAGING TORNADOES |
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Term
| What is a MULTI-CELL THUNDERSTORM? |
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Definition
-They are storms that contain a NUMBER OF CELLS, each in a different stage of development.
**There are 2 TYPES**
1. MESOSCALE CONVECTIVE COMPLEXES (MCC's): circular convective weather system; there are # of individual storms
2. SQUALL LINE: the intense storm cells arranged in a LINE BEFORE A COLD FRONT. |
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Term
| What are the STAGES OF DEVELOPMENT of a THUNDERSTORM? |
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Definition
3 STAGES:
1. Cumulus Stage
2. Mature Stage
3. Dissipation Stage |
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Term
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Definition
-a cloud is DOMINATED by STRONG UPDRAFTS that act to build up storm.
-these UPDRAFTS keep WATER DROPLETS and ICE CRYSTALS SUSPENDED in CLOUD.
-NO rainfall at cumulus stage. |
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Term
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Definition
-begins when WATER DROPLETS are too HEAVY to be SUSPENDED by UPDRAFTS
-UPDRAFTS and DOWNDRAFTS exist SIDE BY SIDE
-RAIN falls from CLOUD
-downdrafts also aided by mixing of COOL, DRIER, ENVIRONMENTAL AIR into cloud CALLED = ENTRAINMENT
-ENTRAINMENT intensifies downdrafts CAUSING HEAVY RAINFALL. |
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Term
| STAGE 3: Dissipation Stage |
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Definition
EVENTUALLY the DOWNDRAFTS dominate the CLOUD and INITIATE DISSIPATION
-there is LIGHT RAIN, then clears up. |
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Term
| What are FACTORS AFFECTING thunderstorm GROWTH and DEVELOPMENT? |
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Definition
- A LOT of instability in air pressure, etc.
-a change in DIRECTION or SPEED of WIND WITH HEIGHT
-MOISTURE |
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Term
| What is the difference between a SEVERE THUNDERSTORM and an ORDINARY CELL STORM? |
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Definition
*SEVERE THUNDERSTORMS consist of: heavy rain, flash floods, hail, tornadoes, strong/gusty surface winds and develop on cold fronts and hurricanes.
*ORDINARY CELL THUNDERSTORMS are: short lasting storms, widely scattered and develop in the middle latitude regions in the summer. |
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Term
| How do THUNDERSTORMS become ELECTRIFIED? |
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Definition
They become ELECTRIFIED through the ELECTRIFICATION OF CLOUDS.
-the electric charges BEGIN WITH FORMATION of HAILSTONES
-the water droplets FREEZE from OUTSIDE IN, and develops a POSITIVELY CHARGED OUTER SHELL and NEGATIVELY CHARGED INTERIOR.
-the interior FREEZES, EXPANDS and outer shell shatters (the POSITIVELY CHARGED fragments are TOSSED UP and heavier NEGATIVELY CHARGED ones remain in the base.
-there's a separation of the charges in cloud and NEGATIVELY CHARGED base REPELS the NEGATIVELY CHARGED ions on surface. |
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Term
| How does a CONDUCTIVE PATH develop? |
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Definition
| -BEGINS with IONIZING AIR between CLOUD BASE and GROUND and the ELECTRICAL FIELD near base FREES ELECTRONS into AIR BELOW. -the IONIZED AIR becomes a CONDUCTIVE PATH also called a LEADER. -STEPPED LEADER (series of steps)-> RETURN STROKE (charges back to cloud)-> DART STROKE (discharge of electrons down SAME PATH) -> PATH REIONIZES, after SEVERAL STROKES, the NEGATIVE CHARGES are WITHDRAWN from the BASE to SURFACE causing a LIGHTNING |
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Term
| What is the FORMATION of TORNADOES? |
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Definition
| They BEGIN with the development of a MESOCYCLONE (a vertical cylinder of ROTATING AIR that is developed in UPDRAFTS of severe thunderstorms) |
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Term
| What are the STAGES of TORNADO formation? |
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Definition
1. The MESOCYCLONE is WIDER, SHORTER, and ROTATING SLOWLY.
2. THEN, MESOCYCLONE stretches DOWNWARDS, NARROWS and rotates FASTER.
3. NEXT, narrowing column of rotating air STRETCHES DOWNWARD TO BASE.
4. It PROTRUDES BELOW CLOUD BASE to produce a DARK, SLOWLY ROTATING WALL CLOUD.
5. The WALL CLOUD develops a FUNNEL CLOUD.. rotating fast, with LOW PRESSURE INSIDE, and HIGH PRESSURE OUTSIDE. |
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Term
| What is the FREQUENCY of TORNADOES IN US? |
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Definition
US has the highest frequency of tornadoes.
-2/3 of tornadoes in the US are F0 or F1 on Fujita scale |
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Term
| What is the TORNADO DISTRIBUTION in the US? |
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Definition
Every state has HAD a tornado.
-The HIGHEST # of occurence in in the TORNADO BELT (tornado alley) in the CENTRAL PLAINS...
**tornado alley includes: TEXAS, OKLAHOMA, KANSAS, MISSOURI, NEBRASKA, IOWA, ARKANSAS, ALABAMA and MISSISSIPPI. |
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Term
| What is the FUJITA SCALE for TORNADOES? |
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Definition
SCALE: MPH: CATEGORY:
EF 0 65-85mph weak
EF 1 86-110mph weak
EF 2 111-135mph strong
EF 3 136-165mph strong
EF 4 166-200mph violent
EF 5 >200mph violent |
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