Lesson 1 - The Atmosphere

Question 1

The atmosphere is a mixture of gases, but it also includes other non-gaseous substances. Such as?

Answer 1

Droplets of water, particles of smoke, dust and ash.

Question 2

Up to a height of 60km the atmosphere remains very?

Answer 2

Constant

Question 3

The approximate composition of ‘dry air’ by volume is…

Answer 3

Nitrogen 78%
Oxygen 21%
Other Gases 1%

Question 4

The other 1% of gases of ‘dry air’ could be…

Answer 4

Argon
Carbon Dioxide
Hydrogen
Carbon Monoxide
Helium

Question 5

Carbon Dioxide although present in relatively low proportions has a significant effect on the global climate because…

Answer 5

It strongly absorbs long wave terrestrial radiation thereby acting as a heat source in the atmosphere.

Question 6

Ozone plays a significant role by…

Answer 6

Absorbing short wave solar radiation, which acts as a heat source on the atmosphere.

Question 7

Water Vapour comprises of which atoms?

Answer 7

Two atoms of Hydrogen
One atom of Oxygen
‘H2O’

Question 8

When water vapour condenses into a liquid it creates weather phenomena such as..

Answer 8

Clouds and Rain

Question 9

In lower atmosphere water vapour can comprise up to…

Answer 9

4% of the total volume.

Question 10

Pressure and density decrease with…

Answer 10

Increasing altitude through all layers.

Question 11

Starting from the surface and going upwards, the atmosphere is divided into four main layers….

Answer 11

Troposphere
Stratosphere
Mesosphere
Thermosphere

Question 12

The boundary layer between each atmosphere layer is known as a?

Answer 12

Pause

Question 13

In the Troposphere the temperature decreases at about..

Answer 13

2’C per 1000ft (1.98’c to be exact)

Known as the lapse rate.

Question 14

About 75% of the mass of air and almost all water vapour is contained in the…

Answer 14

Troposphere

Question 15

Most of the visible weather phenomena take place in the…

Answer 15

Troposphere

Question 16

The Troposphere on average is how thick?

Answer 16

36,090ft (or 11km) above mean sea level (AMSL)

Question 17

The upper limit of the Troposhere is defined by

Answer 17

An abrupt change in the lapse rate.

Question 18

The boundary layer between the troposphere and the stratosphere is called

Answer 18

The Tropopause

Question 19

Temperature is fixed above the Tropopause at what ISA temperature?

Answer 19

-56.5’C (ISA)

Question 20

Over the poles the Tropopause is relatively low, but over the equator it is higher. Why?

Answer 20

Because the height of the Tropopause is determined by the temperature of the air in the Troposphere near the surface. ie The warmer the air the higher the Tropopause, the colder the air the Lower. Think of it like expansion.

Question 21

Tropopause Folds (or breaks) cause abrupt changes in the height of the Tropopause. They occur because of…

Answer 21

the large temperature difference between air masses, the place where fast moving upper air currents (jet streams) are found.

Question 22

Temperature decreases with height upto the…

Answer 22

Tropopause

Question 23

The coldest temperature occurs at the highest….

Answer 23

Tropopause

Question 24

At Sea Level ISA temperature is….

Answer 24

15’C

Question 25

ISA stands for…

Answer 25

International Standard Atmosphere

Question 26

In the Stratosphere temperature is constant to approx…

Answer 26

65,000ft

Question 27

The Stratosphere is generally a good place to fly due to…

Answer 27

- Cloud formation is rare (lack of water vapour and vertical air movement) - Above hazards of the Troposphere (weather phenomena) *Note: Turbulence is still possible*

Question 28

The Ozone layer is generally found at what height?

Answer 28

82,000ft or 25km

Question 29

Temperature is constant in the Stratosphere to what height?

Answer 29

Approximately 65,600ft (or 20km)

Question 30

The temperature rises steadily in the Stratosphere to above 0’C. This is due to?

Answer 30

The Ozone layer absorbing the suns harmful Ultraviolet Light (UV)

Question 31

Without gravity the atmosphere would…

Answer 31

Float off into space. *It becomes an atmospheric pressure by gravity acting on the air mass pulling it down to earth.*

Question 32

In ISA at Mean Sea Level (MSL), temperature is

Answer 32

+15’C

Question 33

In ISA at Mean Sea Level (MSL), temperature lapse rate is

Answer 33

1.98’C per 1000ft (2’C for calculations) *Or* 0.65’C per 100m

Question 34

In ISA at Mean Sea Level (MSL), pressure is

Answer 34

1013.25 hPa *or* 28.92 InHg

Question 35

In ISA at Mean Sea Level (MSL), density is

Answer 35

1.225 Kg/m^3

Question 36

Near the surface assume 1hPa for every **“?”** of height.

Answer 36

30ft

Question 37

At 18,000ft (half way to the top of the Troposphere) assume 1hPa for every **”?”** of height.

Answer 37

48ft

Question 38

At 22,000ft, ISA Density is approximately **”?”** compares to AMSL

Answer 38

50%

Question 39

At 40,000ft, ISA Density is approximately **”?”** compares to AMSL

Answer 39

25%

Question 40

The lapse rate within and between layers is not….

Answer 40

Constant and Uniform