Atmosphere

Question 1

Radius of the Earth

Answer 1

Polar radius of 3432NM

Equatorial radius of 3444NM

Question 2

What’s a Great Circle?

Answer 2

circle on the surface of the Earth with the same centre and the same radius as the Earth itself

Question 3

Rhomb Lines

Answer 3

lines on the surface of the Earth, which crosses the meridians at a constant angle

*flights under 1000NM usually fly along this track

Question 4

Standard Pressure at MSL

Answer 4

1013.25 hPa

Decreases at 1 hPa per 27’

Question 5

Standard Temperature at SL

Answer 5

15° C

Decrease at a rate of 1.98° per 1000’

Question 6

Boyle’s Law

Answer 6

At constant temperature, as the pressure of gas increases, its volume must decrease

Question 7

Charles Law

Answer 7

At constant pressure, if temperature increases, gas expands (volume increases)

Question 8

Density Altitude

Answer 8

Pressure altitude corrected for non standard temperature

DA = PA + (ISA Deviation x 120)

Question 9

Relative Humidity

Answer 9

• Amount of moisture in the air compared to the total amount that can be present at that temperature
• warm air can contain more moisture than cold air

Question 10

Dew point

Answer 10

Temperature at which air reaches a state where it can hold no more water

Question 11

Average Environmental Lapse Rate (ELR)/Saturated Adiabatic Lapse Rate (SALR)

Answer 11

1.8°C/1000’ or 0.6°C/100 m

Question 12

Dry Adiabatic Lapse Rate

Answer 12

3°C/1000’ or 1°C/100 m

Question 13

Dew point lapse rate

Answer 13

0.5°C/1000 ft

Question 14

Layers of the Atmosphere

Answer 14

Troposphere - surface to 11km above (36,000’)

Stratosphere - to 50km (31 miles)

Mesosphere - to 85km (53 miles)

Thermosphere - to 690km (430 miles)

Exosphere - to 10,000 km

Question 15

Importance of Tropopause

Answer 15

• Boundary layer of Troposphere
• traps moisture and associated weather in the Troposphere
• varies with latitude and seasons of the year
• associated with the Jet stream and Clear Air Turbulence (CAT)
• lower in the winter and higher in the summer
• lower at the poles and higher at the equator
• avg of 36,000’ (11 km) at 45º latitude

Question 16

Characteristics of Stroposhpere

Answer 16

• extends upward from Tropopause to approx 160,000’
• temperature generally remains constant at approx -56ºC
• generally smooth with light winds
• turbulence dies out with in the first 1,000’ or less

Question 17

Characteristics of Troposhere

Answer 17

• area where most all flights are conducted
• area of most all weather
• surface to approx 36,000’
• temp decreases with altitude