1. 5.10 Extreme Weather Meteorology 40 Minutes
References: -FTGU, pages 132, 144, 145, 148 to Air Command Weather Manual, Chapters 9 and 15
40 Minutes

2. What type of weather is associated with a: a. cold front
5.10 Meteorology - Review
What type of weather is associated with a:
a. cold front
cumulus clouds, high ceiling, turbulence, showers, good visibility
b. warm front
stratus cloud, low ceiling, smooth air, steady precipitation, restricted visibility
What is an occluded front?
When a cold front catches up to a warm front and the air mixes. Creates variable weather and a TROWAL.
What clouds tell that a warm front is approaching?
Cirrus, Cirrostratus, Altostratus, Nimbostratus, Stratus

3. 5.10 Meteorology – Severe weather
MTPs:
Thunderstorms
Requirements for Thunderstorms
Stages of a Thunderstorm
Thunderstorm Weather
Hazards of a Thunderstorm
Aircraft Icing
Hazards of Squalls and Tornadoes

4. 5.10 Meteorology – Thunderstorms
The basic requirements for a thunderstorm to develop are:
Unstable air
A Lifting Force (generally convection)
High Moisture Content
When are they likely to occur?
With the passage of a cold front
From daytime heating – hot summer days
Interesting Factoid: At any one time there are 1800 TS occurring world wide

5. Stages of a Thunderstorm
5.10 Meteorology – Thunderstorms
Stages of a Thunderstorm
Cumulus stage
Mature stage
Dissipating Stage

6. 5.10 Meteorology – Thunderstorms
Cumulus Stage:
Strong updrafts prevail throughout the cell
Usually no precipitation (yet…)
Temperatures in the cloud are higher than surrounding air.

7. 5.10 Meteorology – Thunderstorms
Mature Stage:
Updrafts of up to 6,000 feet per minute
Downdrafts start in the middle, up to 2,500 ft/min
Precipitation starts as water drops are too heavy for surrounding air to suspend any further
Falling raindrops cause very large, fast downdrafts
Downdrafts of up to 6,000 ft/min at this point
Usually minutes in duration, though may be as long as an hour.

8. 5.10 Meteorology – Thunderstorms
Dissipating Stage:
Entire cell becomes an area of downdraft
Precipitation Stops
Cell loses its energy
Indicated with the top of the cloud forming an anvil shape.

9. 5.10 Meteorology – Thunderstorms

10. 5.10 Meteorology – Thunderstorms
They have very complex weather patterns; wind shear can be found on all sides of the storm
As the thunderstorm matures, strong downdrafts develop and the cold air rushing down spreads out along the ground well in advance, undercutting the warm air - gust front.

11. 5.10 Meteorology – Thunderstorms
Macroburst: A severe and damaging downward rush of air with a diameter of 2 nautical miles or more is called a These can last up to 20 minutes
Microbursts: A downward rush of air with a diameter less than 2 nautical miles and peak winds that last less than 5 minutes
Downdrafts can have vertical speeds as great as 6,000ft/min, with horizontal wind speeds as high as 80 knots

12. 5.10 Meteorology – Thunderstorm Hazards
Lightning
A discharge of electrical energy produced by a thunderstorm
A positive charge collects on the top of the cloud while a negative charge exists on the bottom
Thunder
Created by the rapid increase of temperature (and therefore pressure) of the air around the lightning bolt
Hail – can be crippling to a flying operation
Icing – can occur at any level within the cloud (even when not in cloud!).
Rain – can be very heavy at times
Pressure variance – Altimeter reading errors

13. 5.10 Meteorology – Thunderstorm Hazards
AIRPLANE

14. 5.10 Meteorology – Thunderstorm Hazards
DON’T fly through a thunderstorm!!!!!
Avoid landings and takeoffs near them
Don’t fly under them
Reduce speed at first indication of turbulence
If you fly around one, stay at least miles away, and fly around the right side

15. Aircraft Icing 5.10 Meteorology – Aircraft Icing
Icing increases aircraft weight, drag, stall speed, and decreases lift
Do not fly when there is any contamination to the critical surfaces of an aircraft
Wings, Vertical/Horizontal Stabilizers, Control sufaces, Propeller
Aircraft Icing In-Flight Hazards
Surface
Affect
Control Surfaces
Reduction in lift and controls may become frozen
Canopy
Reduced Visibility
Antennas
Blocked Transmissions
Pitot/Static Tube
Instrument Errors

16. 5.10 Meteorology – Aircraft Icing
Types of Icing
1. Frozen Dew
A white semi-crystalline frost that covers the surface of the aircraft
Frozen dew happens on cold clear winter nights
Water vapour hits the surface of the aircraft and sublimation occurs

17. 5.10 Meteorology – Aircraft Icing
2. Hoar Frost
a white, feathery, crystalline formation that covers the entire surface of the aircraft
Very similar to frozen dew
The only difference is that hoar frost can happen during flight.

18. 5.10 Meteorology – Aircraft Icing
3. Rime Ice
An opaque, or milky white ice that accumulates on the leading edge of the wing, and on antennas
It is formed by the almost instantaneous freezing of small supercooled water droplets
This fast freezing causes air pockets to be trapped in the ice, giving the opaque quality.

19. 5.10 Meteorology – Aircraft Icing
4. Clear Ice
A heavy coating of glass like ice which forms over the entire surface (or a good portion of it) of a wing
It is formed as large supercooled water droplets freeze slowly as they move rearward to cover the wing
Most often occurs with temperatures between °C

20. 5.10 Meteorology – Squall Line
Long line of squalls and thunderstorms which sometimes accompanies the passage of a cold front
Usually associated with a fast moving cold front undercutting an unstable warm air mass
May form anywhere from 50 to 300 nautical miles in advance of the front.

21. 5.10 Meteorology – Tornadoes
Violent, circular whirlpools of air associated with severe thunderstorms
Very deep, concentrated low pressure areas
Shaped like a funnel hanging out of the cumulonimbus cloud
Dark in appearance due to dust and debris sucked in
Diameter ranges from 100 feet to half a mile
Move at speeds of 25 to 50 knots
Wind speeds as great as 300 knots.

22. 5.10 Meteorology – Confirmation
1. What 3 things are needed for thunderstorm to develop?
______________________________
2. What are the 3 stages to a thunderstorm?

23. 5.10 Meteorology – Confirmation
3. Name the following ice types
4. Where are squall lines found?