Atmosphere Pressure Flashcards
Pressure Lapse Rate ISA
1hpa per 30ft
1hpa per 9m
Surface Pressure Charts
Predict strength/direction of wind
Isobars = lines of equal pressures
Measure on QFF
Ridge
Extension of a high pressure system
Trough Line
Low pressure on chart indicate strong surface convergence…AVOID
Pressure vs ALT
Low to High Pressure - Increase in height
High to Low Pressure - Decrease in height
Pressure vs Temp
High to low temp - Danger (pressure decreases more rapidly with height)
Low to High Temp - Increase in height (pressure decreases more slowly with height)
Isohypes
Show height variation of constant pressure
QNH
Pressure at MSL (calculated from QFE with ISA lapse up or down)
QFE
Field elevation pressure (accurate/measure)
QFF
Sea level pressure calculated from QFE BUT using actual pressure lapse rates
QFF vs QFE
Warmer Air - QNH will be greater than QFF (Actual lapse rate would be less than ISA)
Colder Air - QNH will be less than QFF (Actual lapse rate would be more than ISA so decreases more)
Constant pressure chart
Chart that plots heigh of pressure levels
How to find pressure at an altitude (formula)
1013 * FL/1000
On a synoptic chart how will the flow of air move in a divergent column of air
Away from the area of divergence across the isobars marked on the chart
