Flashcards in CH3 - Atmosphere Pressure Deck (19)
What are the isobars?
Lines with equal pressure
What are the 3 different patterns of the isobars?
Col, troughs and ridge.
What happen if the isobars are close?
The closer the greater pressures are created. More forces are implicated.
Which values from the table of pressure against height are the most important ones?
10 000ft = 700
18 000ft = 500
30 000ft= 300
38 000ft = 200
53 000ft = 100
What is the change of pressure (hPA) with height (ft) at MSL?
27 hPA - 1 ft
What is the change of pressure with height at 30 000ft e.g.? (Formula)
96 x Temp (K) / *the corresponding value* (300 in this case)
Which is 73 ft per 1hPA.
What is QFE?
(Q Field Elevation)
It's the actual pressure at the current ground level (airfield).
E.g. ... in altimeter to display zero feet.
What is QNH?
(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.
What is QFF?
Pressure at MSL taking into account the actual temperature conditions.
What is QNE?
It is NOT pressure. QNE is ELEVATION (1013 hPA)
How are the values for QFF respectively to QNH taking into acount cold and warm air?
Warm QFF < QNH
Cold QFF > QNH
Warm QFF > QNH
Cold QFF < QNH
What is SPS?
Standard Pressure Settings.
Is the standard atmosphere presure at sea level according to ISA (International Standard Atmosphere) and US Standard Atmosphere.
Vertical distance above a reference point (commonly terrain elevation).
Distance from/to MSL. How high an aircraft is above mean sea level.
Define True altitude.
It's the actual elevation above mean sea level.
It's used to indicate how high an airport or a terrain is above MSL.
Define Pressure altitude.
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.
Define Density altitude.
It's the altitude corrected for non-ISA atmospheric conditions.
Density Altitude: Pressure Altitude + 120 (OAT - ISA Dev.)