Cap 14 Thunderstorms

Question 1

3 main things to form a TS ?

Answer 1

DEEP UNSTABLE AIR
A LOT OF MOISTURE
A TRIGGER TO CAUSE THE RISE

Question 2

STAGES OF A TS?

Answer 2

INTIAL STAGE>>
Only up draughts,
speed 30 m/s ,
cumulus,tcu ,cb
Last 15/20 min

MATURE STAGE»
Up draughts (speed 10000ftm) and down draughts speed(2000/6000ftm)
Precipitation begins
Last 15/30 min

DISSIPATING STAGE>>
Only downdraft
No more supply of moisture
Light rain
Last 1.5 to 2 hours

Question 3

Thunderstorm types?

Answer 3

Single cell»Isolated cell ,can produce hail microburst winds

Ts clusters (multi cell)»develop in numerous cells,cover large area

Squall line»a line of CBs ,usually along trough line,ITCZ,cold front

Supercell»self sustaining thunderstorm which can produce also tornados at the ground.

Question 4

Ts single cell

Question 5

Mcs (mesoscale convective system)?

Answer 5

Collection of TS that act a s a system
Spread across entire state and last more than 12 hours
On radar these appear as a solid line or cluster of cells

Question 6

MCC(mesoscale convective complex)?

Answer 6

Is a particular type of MCS
It is a large circular long lived cluster of showers and TS identified by satellite
Area of cloud top at least 100000km2 at a temp of -32c or less.Or and area of cloud top at least 50000km2 at a temp of -52 or less

Question 7

At what distance gust front turbulence can spread?

Answer 7

Up to 15/20 nm ahead of the storm cell

Question 8

Microburst ?

Answer 8

Rapid descending air in powerful CBs

Last up to 5 min with a diameter less than 4km

Question 9

Macroburst?

Answer 9

The precipitation takes with it the surrounding air with it and creates a downdrafts and then it spreads laterally near the ground.
Size +4 km and last 5/20 min
Downdrafts often 6000ftm wind more than 50kt

Question 10

Virga

Answer 10

When the precipitation falls it evaporates and latent heat is absorbed makinfg the air around colder and then it sinks making downdraughts.
Difficult to detect

Question 11

Where is most likely to encounter Hail(GR) in TS?

Answer 11

At the center of the core ,top and downwind side of the anvil of the TS (shooting from top of the cloud).
So best way to avoid is to stay on upwind

Question 12

Types of lightning?

Answer 12

> cloud to air (CA)
cloud to ground (CG)
intra cloud (IC)
cloud to cloud (CC)

Question 13

St elmos fire phenomena?and types of instrument error?

Answer 13

“Blue plasma discharge “ due to friction for exemple With ice,dust,volcanic ash
And may make in error the altimeter,vsi,asi,adf compass

Question 14

Describe a tornado?

Answer 14

Requires a super cell TS
Strong inward convergence and updraft intensifies and narrow the tornado.
Avg diameter 100m 150m
Wind can exceed 200ktthey are most frequent in
spring and summer especially in north USA

Question 15

WATER spouts?

Answer 15

A tornado over water

Question 16

Dust devils (PO)?

Answer 16

Range from 10 -100ft wide
Can reach up to 650 ft in height
Occur in hot ,calm ,dry conditions

Question 17

How the amount of TS are describe in SIGWX Chart?

Answer 17

> isolated (ISOL) coverage less than 50%
occasional (OCNL) COVERAGE 50/75%
FREQUENT(FRQ) OVER 75%

CAN ALSO BE EMBEDDED (EMBD)

Question 18

How to avoid TS?(distance to maintain)

Answer 18

> if over flown ,5000ft vertical separation

>lateral 20nm separation,but can be 10nm below 20000ft using Weather radar

Question 19

What is a stormscope ?

Answer 19

A lightning detector,scanning 120 degrees within 200nm radius