Meteorology

Question 1

Layers of the Atmosphere (T, T, S, S, M, M, T, T, E)

Answer 1

Troposphere
Tropopause
Stratosphere
Stratopause
Mesosphere
Mesopause
Thermosphere
Thermopause
Exosphere

Question 2

Troposphere

Answer 2

Lowest layer
Contains most of the water vapour in the atmosphere
Temperature decreases as altitude increases
Majority of weather and clouds occur here

Question 3

Tropopause

Answer 3

Upper boundary layer of the troposphere
The temperature has dropped to about -56C
Jet streams, CAT, thunderstorms

Question 4

Stratosphere

Answer 4

Extends to 160,000’
Temperature increases as altitude increases
Initially, -56 C but gradually rises to 0 C
Strong vertical air motions
Some weather can extend into stratosphere

There is virtually no weather above the stratosphere.

Question 5

The Standard Atmosphere

Answer 5

At sea level:
Air is a perfectly dry gas
Temp 15°C
Standard lapse rate Temp changes 1.98°C per 1000 ft
Pressure 29.92”hg or 1013.25mb at sea level

Question 6

Pressure - the “Compressibility” of air.

Answer 6

Air is not empty space.

It has mass and weight just like any other solid, liquid, or gas.

Question 7

Density = is mass per unit of volume.

Answer 7

affected by temperature.
Warm air molecules move around faster and take up more space.
(warm air is less dense).

Question 8

The Barometer

Answer 8

The more force applied to the surface of the mercury in the bowl, the higher the mercury rises in the tube.

Question 9

Units of Measurement
A pressure decrease or increase equals 1 inch of mercury per 1000’.
Ex:

Answer 9

01.00 = 1000’

29.92 Hg is standard pressure for sea level (ISA).
If the pressure were to rise or fall 1 “Hg, the result would be:
30.92 = -1000’
28.92 = +1000

Question 10

Station Pressure

Answer 10

The actual weight of air (pressure), at the station.

Question 11

Sea Level Pressure

Answer 11

The pressure calculated down to mean sea level pressure; or, the station pressure plus the weight of the air extending from the station to mean sea level

Question 12

City A is at sea level with pressure of 29.92 Hg

–City B is at 5000’ MSL what is their Hg?

Answer 12

5,000 = 5.0 Therefore 29.92 -5.0 = 24.92.

Remember when higher in the air (+5,000ft) = less pressure = take away from the mercury reading.

Question 13

Density Altitude

Answer 13

is pressure altitude corrected for temperature.
“Density altitude is the altitude the airplane feels it is at.”
–airplane will be most vulnerable to a high density altitude during takeoff.

Question 14

Pressure Systems

Answer 14

govern the evolution of fronts and weather.

Question 15

Low Pressure Systems

Answer 15

• -aka: depression or cyclone.
• -Winds converge at surface = upward motion
• -Winds flow counterclockwise and toward a low.
• -weather associated with a low is always bad however the temperature becomes more stable
• -may cover anything from a very small localized area to half a continent.

Question 16

High Pressure Systems

Answer 16

aka: anti-cyclone.
- -Winds blow clockwise and away from a high
- -Winds converge at altitude = descend then diverge at the surface.
- -Weather is usually fair and clear.

Question 17

Convergence and Divergence

Answer 17

–always flow away from highs and towards lows.

Question 18

Isobars

Answer 18

These are lines of equal pressure depicted on a pressure map

• these lines circle areas of pressure and never cross
• separated by 4 millibars (another word for hpa) intervals

Question 19

Ridge

Answer 19

A ridge is an elongated area of high pressure

–Fine to fair weather can be expected.

Question 20

Trough

Answer 20

A trough is an elongated area of low pressure.

Poor frontal weather can be expected.

Question 21

Col

Answer 21

A col is an area of neutral pressure.

Weather can be unpredictable.

Question 22

Wind and Pressure Gradient

[pressure gradient = rate of change of pressure over a given distance]

Answer 22

• -Isobars spaced closely together indicate rapid change of pressure = Expect strong winds.
• -Isobars spaced further apart indicate slow change of pressure = Expect light winds

Question 23

Coriolis Force

Answer 23

air is influenced by earth’s rotation.
doesn’t flow in straight lines
–high to a low. It is deflected to the right (north)
–deflected to the left in southern hemisphere
Deflection is more pronounced at the poles and zero at equator.

Question 24

Buy-Ballot’s Law

Answer 24

northern hemisphere, winds blow

• -counterclockwise around low pressure (cyclone)
• -clockwise around a high (anticyclone).

stand with your back to the wind, the low pressure will always be on your left.

Question 25

Surface Friction

Answer 25

The reduction of wind speed decreases the Coriolis effect, causing wind to flow outward from a high, and inward to a low.

Question 26

Veer

Answer 26

A wind change in a clockwise direction

In a climb, wind usually veers and increases.

Question 26

Back

Answer 26

A wind change in a counter-clockwise direction.

In a descent, wind usually backs and decreases.

Question 27

Gusts

Answer 27

A rapid irregular fluctuation in the upward and downward movement of air currents.

Question 28

Squalls

Answer 28

A sudden and sustained increase in the strength of wind lasting longer than a gust.

Question 29

Land Breezes

Answer 29

winds blow from land –> sea
at night
when the land is cooler than the water.

Question 30

Sea Breezes

Answer 30

winds blow from sea –> land
during the day
when the water is cooler.

Question 31

Valley Breezes

Answer 31

These anabatic winds flows up the slope of a valley during the day, when the air on the sun-facing side becomes warmer and rises.

Question 32

Mountain Breeze

Answer 32

These katabatic winds flow down the slope of a valley at night as the air is cooled and is pulled down the slope by gravity.

Question 33

Mountain Wave

Answer 33

air flows over a ridgeline it also flows down the other side = oscillations or waves to occur.

• -can last for several hours
• -can reach up to 30 nm past the mountain range.

Question 34

Mountain Wave Clouds (3 types)

Answer 34

1) Cap Cloud - Forms along top of ridge and the wind carries it downstream.
2) Lenticular - Lens shaped clouds that form along the crest of wave.
3) Rotor Clouds - Form in eddies downstream about ridge height.

Question 35

Wind Shear

Answer 35

A distinct change in wind speed and/or direction.

Question 36

Types of wind sheer (2)

Answer 36

1) Performance Increasing Shear
Increased head wind
Airspeed increased, aircraft comes in high, overshoots runway
2) Performance Decreasing Shear
Decreased head wind
Airspeed decreases, potential stall at low altitude, undershoots runway