Meteorology Flashcards
What are the ISA conditions?
+15C, 1013.25hpa, 1.225 Kg/m^3 density
What are the ISA lapse Rates?
Temperature = 1.98C/1000ft to 36090ft at -56.4C tropopause.
Pressure = 30ft/hpa to 5000ft then at a slower rate after
Density = 120ft per unit of density change for every 1C change.
What are the main requirements for thunderstorm formation
Warm & Moist Air
Unstable Atmosphere
Trigger Mechanism for lifting
Mechanism for buildup of electrical charge difference
What are the 3 stages of a thunderstorm’s life cycle?
Growing Stage
Maturing Stage
Decaying Stage
What are the primary differences between radiation fog and advection fog?
Radiation fog is formed due to a surface cooling, advection fog requires a surface already cold.
Radiation fog mainly forms during the night. Advection Fog can form anytime and last much longer.
Radiation for cannot form over the water, advection fog can form over land or water.
What are the primary requirements for radiation fog?
Clear sky - to allow terrestrial radiation to escape
light wind - to encourage mixing of air
stable atmosphere, so cool air settles near surface.
High relative humidity.
What is relative humidity?
Relative humidity is the amount of water vapour in the air compared to the amount of water vapour that could be in the air if it were 100% saturated.
When are METAR’s and Auto METAR’s issued?
METAR issued every 1 hour.
Auto METAR issued every 30 minutes.
When are SPECI’s issued?
SPECI’s are issued off the hour in METAR code.
What are METARs?
METARs are manual reports based off observation. They are issued every hour.
What are Auto METAR?
Auto METAR’s are automated observations which are issued by Automatic Weather Stations every 30 minutes.
What are SPECI’s?
Special Aerodrome Reports issued off the hour. They are provided as part of METARs. Only if weather has changed significantly.
What is a trend?
TREND is appended to auto METAR at NZAA, NZCH, NZWN and to military METAR.
RVR
Used to report visibility less than 1500m. Installed at Auckland.
What does // mean?
WX not detected due sensor temporarily inoperative.