Aviation Meteorology

Question 1

The atmosphere is split vertically into 4 layers, but where does most aviation weather take place?
-troposphere
-stratosphere
-mesosphere
-thermosphere

Answer 1

Troposphere

Question 2

What is the tropopause?

Answer 2

It is the boundary between the troposphere (lowest) and stratosphere and its height varies depending on latitude (position on earth)

Question 3

What happens to temperature in the troposphere and stratosphere?

Answer 3

In the troposphere it falls as you gain altitude until you hit the stratosphere where it remains constant

Question 4

What happens to air movement in the troposphere and stratosphere?

Answer 4

In the troposphere hot air rises and cold air sinks so there is mixing and vertical movement. In the stratosphere however it is limited as the air stays the same temp (roughly -57 celcius)

Question 5

What happens to water vapour in the troposphere and stratosphere?

Answer 5

In the troposphere there is alot of water vapour leading to cloud formation but in the stratosphere there is little water so it is generally clear of cloud.

Question 6

What are the main components of air?

Answer 6

Nitrogen and oxygen

Question 7

What air has more potential to carry water vapour?

Answer 7

The warmer the air the greater its potential to carry water vapour. The amount if vapour depends on surface moisture

Question 8

What is the definition of international standard atmosphere (ISA)?

Answer 8

It is a general atmosphere used to compare with the real atmospheres variation.
It is completely dry and pressure and temperature all decrease as altitude is gained. (-2 degrees per 1000ft)

Question 9

Using the ISA, how much does pressure decrease as you climb?

Answer 9

Aprox. 1hPa per 30ft

Question 10

Using the ISA, how much does temperature decrease?

Answer 10

Aprox. -2 degrees per 1000ft

Question 11

What are isobars?

Answer 11

They are lines that join places with the same sea level pressure on an atmospheric pressure map. The space in between the isobars is the pressure gradient.

Question 12

What does it mean if isobars are close together?

Answer 12

The pressure is fluctuating and the pressure gradient is strong

Question 13

What does it mean if isobars are far apart

Answer 13

The pressure changes are gradual and the pressure gradient is weak

Question 14

How does low air density affect aircraft performance?

Answer 14

The aircraft will require more airspeed to achieve lift, less air means a weaker burn so the engine is weaker but more fuel efficient, less drag, and potentially not enough air for humans to breathe.

Question 15

How does high air density affect aircraft performance?

Answer 15

Less airspeed required for take off, more air means a stronger burn so the engine is more powerful but less fuel efficient, more drag, more likely to have enough air for breathing

Question 16

What happens to air density as altitude increases?

Answer 16

Air denstity goes down

Question 17

If air has more water molecules in it, what happens to air density?

Answer 17

It decreases

Question 18

Why might a plane perform slightly worse on a damp day?

Answer 18

Because air density is reduces as there is more water vapour in the air in comparison to a dry day

Question 19

If your altimeter is set to read 0ft at sea level, what should it read if the pressure drops by 1hpa?

Answer 19

It will read 30ft as it thinks that due to the decreased air pressure the plane has gained altitude (as air pressure decreases with height)

Question 20

If you enter an area with lower pressure but you dont change your altimeter setting and you cruise at the same indicated altitude, what will happen?

Answer 20

You will descend to the ground. This is because as you enter an area with lower pressure the altimeter thinks you are ascending so you will pitch down to counter this, but in reality you are just flying lower