Thunderstorm

Question 1

3 Requirements for a Thunderstorm

Answer 1

1. Unstable Air
2. High Humidity
3. Trigger

Question 2

Name the 4 triggers of a thunderstorm

Answer 2

1. Orographic
2. Frontal
3. Convection
4. Convergence

Question 3

Name the 3 stages of a Thunderstorm

Answer 3

1. Building/Initial/Cumulus Stage
2. Mature Stage
3. Dissipating Stage

Question 4

Building/Initial/Cumulus Stage

Describe what happens.

Answer 4

All updraught.
Vertical speeds can be 60kts (30m/s).
Lasts 15-20 min.

Question 5

Mature Stage

Describe what happens.

Answer 5

Updraught and Downdraught.
Anvils are formed.
Precipitation starts (Rain&Hail).
Vertical Windspeeds can be 100kts or 50m/s or 10’000ft/min.
Positive charge develops at the top of cloud & negative charge at the bottom.
Lightning Starts.
Lasts 15-20 min.

Question 6

Lightning usually occurs between what temperatures:

Answer 6

-10C and +10C.

Question 7

What’s a Gust front?

Answer 7

Downdraughts from Thunderstorms to the sides of it. Can be up to 6000ft in depth and can appear 15-20nM before the Thunderstorm cloud.
Can form a Roll cloud.

Question 8

Microburst

Answer 8

Strong Down currents from Thunderstorm clouds.

Affects an area up to 5km (3nM) and for up to 5 min.

Question 9

Macroburst

Answer 9

Strong down currents from Thunderstorm clouds.

Affects an area over 5km and for more than 5 min.

Question 10

Dissipating Stage

Answer 10

Only downdraught.

Can last 1.5-2.5hrs.