14 Thunder Storms Flashcards
1
Q
Conditions required for a thunderstorm
A
- Unstable air
- Humidity
- Trigger
2
Q
Triggers for a thunder storm
A
- Orthographic
- Frontal
- Thermal / Convection
- Low Pressure / Convergence
3
Q
Types of Thunderstorm
A
- Frontal - warm air is forced up and over a cold front
- Air Mass - Cold air moves in over a warm surface. Air is heated from below via conduction which then rises
- Heat/Thermal - Surface reaches its hottest point in the afternoon so ELR > DALR as air is heated from the surface.
- Squall Line - Line of thunderstorms along a cold front. Multi-cell storm. Most severe conditions.
4
Q
Name the phases of a Thunderstorm
A
- Initial / Cumulus / Building
- Mature
- Dissipating
5
Q
Key facts on Cumulus stage of a thunderstorm
A
- Up drafts build the cloud up
- Up drafts can reach speeds of 60kts
- Area of low pressure can developers underneath due to up drafts
- Lasts 15 to 20mins
6
Q
Key facts about the mature stage of a thunderstorm
A
- Strong up drafts and down drafts
- Latent heat absorbed (Evaporation) - stronger downdrafts
- Rain and Hail
- Updrafts up to 100kts
- Static charge developed by friction between perspiration
- Positive at top, negative at bottom
- Lightning - between -10 and +10 degrees C
- Front gusts 15-20 miles in front - Roll cloud
- Microbursts, area <5km, <5mins
- Macrobursts, area >5km, >5mins
- Lasts 15 to 20 mins
- Max height - 60 to 70K Ft
- 6000ft from surface
7
Q
Key facts about Dissipating stage of a thunderstorm
A
- Downdrafts overcome updrafts
- Sinking air evaporates - cloud disperses
- Lasts 1.5 to 2.5 hours
8
Q
Speed of thunderstorm:
A
15 - 20kts
- Frontal storms travel the speed of the front
- These are the fastest storms
9
Q
Where in a storm are tornadoes found?
A
Trailing edge of a super cell
10
Q
Diameter of a tornado
A
100 to 150m
11
Q
Ground speed of a tornado
A
20 - 40kts
12
Q
Wind speeds in a tornado
A
200kts
13
Q
How long do tornados last?
A
Up to 30mins
14
Q
Where on the globe are tornados mostly found?
A
Mid-west USA
Late spring to early summer
15
Q
How are tornados measured?
A
On the Fujita scale
