CH3 - Atmosphere Pressure

Question 1

What are the isobars?

Answer 1

Lines with equal pressure

Question 2

What are the 3 different patterns of the isobars?

Answer 2

Col, troughs and ridge.

Question 3

What happen if the isobars are close?

Answer 3

The closer the greater pressures are created. More forces are implicated.

And viceversa.

Question 4

Which values from the table of pressure against height are the most important ones?

Answer 4

10 000ft = 700
18 000ft = 500
30 000ft= 300
38 000ft = 200
53 000ft = 100

Question 5

What is the change of pressure (hPA) with height (ft) at MSL?

Answer 5

27 hPA - 1 ft

Question 6

What is the change of pressure with height at 30 000ft e.g.? (Formula)

Answer 6

96 x Temp (K) / the corresponding value (300 in this case)

Which is 73 ft per 1hPA.

Question 7

What is QFE?

Answer 7

(Q Field Elevation)
It’s the actual pressure at the current ground level (airfield).

E.g. … in altimeter to display zero feet.

Question 8

What is QNH?

Answer 8

(Q Nautical Height)
Pressure at MSL applying ICAO’s standard atmosphere corrections to QFE, which is > [QFE + Elev. / 27hPA]

E.g. When sitting on the ground at an airport, dialing QNH into the altimeter will cause it to display the airport’s altitude above sea level.

Question 9

What is QFF?

Answer 9

Pressure at MSL taking into account the actual temperature conditions.

Question 10

What is QNE?

Answer 10

It is NOT pressure. QNE is ELEVATION (1013 hPA)

Question 11

How are the values for QFF respectively to QNH taking into acount cold and warm air?

Answer 11

AMSL
Warm QFF < QNH
Cold QFF > QNH

BMSL
Warm QFF > QNH
Cold QFF < QNH

Question 12

What is SPS?

Answer 12

Standard Pressure Settings.
Is the standard atmosphere presure at sea level according to ISA (International Standard Atmosphere) and US Standard Atmosphere.

Question 13

Define Height.

Answer 13

Vertical distance above a reference point (commonly terrain elevation).

Question 14

Define Altitude.

Answer 14

Distance from/to MSL. How high an aircraft is above mean sea level.

Question 15

Define True altitude.

Answer 15

It’s the actual elevation above mean sea level.

Question 16

Define Elevation.

Answer 16

It’s used to indicate how high an airport or a terrain is above MSL.

Question 17

Define Pressure altitude.

Answer 17

It’s the elevation above a standard datum air-pressure plane.

Pressure altitude is the height above a standard datum plane (SDP), which is a theoretical level where the weight of the atmosphere is 29.92 “Hg (1,013.2 mb) as measured by a barometer.

Question 18

Define Density altitude.

Answer 18

It’s the altitude corrected for non-ISA atmospheric conditions.

Aircraft performance.

Formula:
Density Altitude: Pressure Altitude + 120 (OAT - ISA Dev.)

Question 19

Define Flight Level (FL).

Answer 19

Heights above 1013.25 pressure level. How high an aircraft is above what would be mean sea level in a perfect standard atmosphere.