Lesson 1

Question 1

Describe the structure of the Atmosphere

Answer 1

The atmosphere is divided into 2 groups of constituents.

1- Permanent constituents ( NOT - Nitrogen 78%, Oxygen 21%, Trace Gases 1 %)

2- Variable constituents ( 3 states of matter)
• solids - dust, salt, volcanic ash
• liquids - water droplets, clouds
• gases - water vapour etc

Question 2

State the 4 main layers of the atmosphere

Answer 2

1- Troposphere
2- Stratosphere
3- Mesosphere
4- Thermosphere

Question 3

State the 3 boundaries separating the 4 atmosphere layers

Answer 3

1- Tropopause (36000ft & -56 degrees C)
2- Stratopause (160,000ft & 0 degrees C)
3 Mesopause (280,000ft & -90 degrees C)

Question 4

What is atmospheric pressure

Answer 4

• It is the weight the atmosphere exerts on you.
• Pressure at any level is due to the weight of air in the column above that point
• Note, pressure falls with height and is therefore greatest at ground level

Question 5

What units are used to report pressure in the UK and in the US

Answer 5

UK = HPa (Hector Pascals)
US = Inches of Mercury (In Hg)

Question 6

Describe how pressure changes as you fly upwards through the atmosphere

Answer 6

Pressure decreases with height. It will decrease by 1HPa per 30ft climbed

Question 7

How does temperature and pressure affect the density of the atmosphere

Answer 7

Density is affected by PAWT (Pressure, Altitude, Water Vapour and Temperature)

As Pressure increases, air density increases - they are directly proportional

As temperature decreases, air density increases- they are inversely proportional

However, as we increase altitude the temperature will drop implying an increase in air density. BUT pressure also drops which implies a decrease in air density. The pressure effect wins and that leads to density decreasing with altitude.

Question 8

State the following values from the International Standard Atmosphere or ISA; 1) Mean sea level (MSL) temperature? 2) Temperature lapse rate? 3) Height of the Tropopause? 4) Temperature at the tropopause?

Answer 8

1) MSL Temp = 15 degrees C
2) 2 degrees C per 1000ft
3) 36,090ft
4) -56,5 degrees C

Question 9

Name 2 gases found in the troposphere and one significant gas found in the stratosphere

Answer 9

Troposphere- Nitrogen & Oxygen

Stratosphere- OZONE

Question 10

How does temperature change with height in the troposphere and stratosphere

Answer 10

In the troposphere temperature will decrease with height with the Temp Lapse rate of 2 degrees C per 1000ft. Reaching -56 degrees C at the tropopause.

In the stratosphere temperature begins to increase with height until it reaches 0 degrees C at the Stratopause

Question 11

At what point in the stratosphere is the heighest temp found?

Answer 11

0 degrees C - Stratopause

Question 12

In warm climates would you expect the tropopause to be high or low

Answer 12

High with a colder temperature Approx -80

Compared to avg UK temp of -56 and a low tropopause

Question 13

What instrument is used to measure pressure?

Answer 13

Barometer

Question 14

Names 3 units for measuring pressure

Answer 14

Hector Pascals, inches of Mercury, millibars

Question 15

State ISA Values for;

1) MSL pressure
2) MSL Temp
3) MSL Air density
4) Temp lapse rate
5) Tropopause temp
6) Tropopause hgt

Answer 15

1) 1013.25 HPa
2) 15 degrees C
3) 1.225 kg/m3(cubed)
4) 2 degrees fall per 1000ft
5) -56 degrees C
6) 36,090 ft