Met Flashcards
What layers does the atmosphere on Earth have (from low to high altitude)?
- Troposphere
- Stratosphere
- Mesosphere
- Thermosphere
- Exosphere
Dry gasses and their percentage
Nitrogen - 78%
Oxygen - 21%
Other gasses - 1%
What 5 meteorological stats does an aircraft meassure and at what rate does the aircraft send it?
- Temperature
- Pressure
- Wind
- Humidity
- Density
Every 30 min
Pressure formula?
Pressure = depth * density
ICAO ISA
- pressure
- Base temperature
- Density
- Pressure lapse rate
- Temperature lapse rate
- pressure: 1013,25 hPa
- Base temperature: 15 degrees Celcius
- Density: 1,225 kg/m3
- Pressure lapse rate: 27 ft/hPa
- Temperature lapse rate: 1,98 degrees Celcius per 1000 feet
What are the two types of measurement equipment used to measure wind?
Anemometer
Windsock
What are the two types of measurement equipment used to measure horizontal visibility?
Transmissometer
Scattermeter
Honorable mention: looking out of the window
What is the measurement equipment used to measure the cloud base altitude?
Ceilometer
What is the measurement equipment used to measure air temperature?
Thermometer
What is the measurement equipment used to measure the dew point temperature?
Hygrometer
(Two types: hair hygrometer and wet/dry bulb hygrometer)
What are the two types of measurement equipment used to measure pressure?
Dual sensor
Barometer
What does an Automated Weather Observation System (AWOS) measure?
Everything meteorological:
Wind
Horizontal visibility
Vertical visibility
Weather
Clouds
Temperature
Dew point
Pressure
Why is volcanic ash dangerous for aircraft?
The sand particles get converted into glass due to the high temperature in the engines, causing damage and jamming of the engines
What are the three cells in the troposphere called (from equator to the north pole)?
Hadley Cell
Ferrel Cell
Polar Cell
True/false: Temperature always decreases with an increase in altitude
False, temperature can also stay constant or increase with an increase in altitude
What are the 3 ways of transferring energy?
Radiation: transfer of energy between bodies that are not in contact
Conduction: transfer of energy between bodies in contact (without movement)
Convection: transfer of energy by vertical movement
The process through which clouds are formed is called…
Condensation
True/false: warm air can hold more water than cold air
True.
What % of accidents are weather related?
About 28%
- In the northern hemisphere, high pressure areas always rotate …
- In the northern hemisphere, low pressure areas always rotate …
- Clockwise (to the right)
- Counterclockwise (to the left)
How many hPa difference is there between two isobars?
4 hPa
What is the average slope of a warm front? And a cold front?
150:1 for warm
50:1 for cold
When can the term CAVOK be used?
Vis > 10 km
No CB or TCU
No cloud below 5000 ft or Min Sector Alt (whichever is greater)
No sig weather at or in the vicinity of the aerodrome
How is heat transferred within the atmosphere?
Convection, because air is a very poor conductor of heat conduction is almost 0.
What are three factors that contribute to a low density?
Hot
Humid
High
What are other factors that can cause air to rise, next to convection?
- Frontal lifting
- Orographic lifting
- Thermal convergence
- Thermal turbulence
- Mechanical turbulence
What are the different types of air masses?
- Polar
- Tropical
- Arctic (extreme Polar)
- Equatorial (extreme Tropical)
Continental or Maritime
Is an anticyclone an area of high or low pressure?
High pressure
What is a low pressure area called?
Depression or Cyclone
What is a nimbus cloud?
A rain bearing cloud
How much more energy does it cost to heat water in contrast to soil?
5 times more energy
What is cloud base?
The height of the base of any cloud above aerodrome elevation.
What is cloud ceiling?
The height of the lowest part of any cloud visible from the aerodrome which is sufficient to obscure more than one half of the sky visible.
From which type of clouds is Drizzle falling?
Always falls from stratus clouds
Never falls as showers and never from clouds with a height greater than 1500 ft above terrain.
What are Supercooled water droplets?
Water in liquid form with a temp below -0 degrees celcius.
What are the most dangerous SCWD?
They exist between -0 and -10 degrees where the droplets can be relatively big.
Which types of clouds is rain falling from?
Nimbostratus, altocumulus, cumulus, and cumulonimbus
Which types of clouds is snow falling from?
Nimbostratus, thick altocumulus or stratocumulus.
In which cloud is hail formed?
Only formed in cumulonimbus clouds.
What are the three types of hail?
Snow pellets / sof hail (not proper hail)
Small hail - when largest hailstone is < 5 mm
Hail - when largest hailstone > 5 mm
Name the requirements for thunderstorm?
Moisture
Instability
Trigger
What is the definition of a microburst?
A downburst falling from a CB affecting an area of 4 km in diameter or less.
What is the most common type of thunderstorm in northern Europe in summer and early autumn?
Convectional CB
What are the 5 types of icing?
Hoar frost
Cold soaked fuel frost
Rime ice
Clear ice
Rain ice (freezing rain)
What is rime ice?
Rough, opaque coating produced by small supercooled droplets that freeze almost completely on impact.
It is porous, fragile and weak and therefore unlikely to form large accumulations although it can affect aerodynamic properties and block small air intaks.
What is clear ice?
Transparent or translucent ice form by large dorplets that are only just supercooled.
It is heavy and difficult to see and to remove with de-icing methods,
What is rain ice?
Most dangerous form of icing and is caused by large rain droplets that are just above 0 degree falling onto an airframe that is below 0 degrees.
Most likely place for an a/c to encounter rain ice is flying in cold air just ahead of a warm front.
What are the two clouds that are particularly associated with severe icing?
Cumulonimbus
Nimbostratus (because of length of exposure)
Why is wind speed not critical for advection fog?
The fog will exist because warm high humidity air is cooled by contact with a cold surface, to cause condensation.
What is the averaging period for a METAR/SPECI? And for a MET-REPORT?
10 minutes
2 minutes
Name the different Descriptors in a METAR
MI - Shallow <2m
BC - Patches
PR - Partial
DR - Low drifting <2m
BL - Blowing >2m above ground
SH - Showers
TS - Thunderstorm
FZ - Freezing (supercooled)
Name the different Precipitation in a METAR
DZ - Drizzle
RA - Rain
SN - Snow
SG - Snow grains
PL - Ice pellets
GR - Hail
GS - Small hail and / or snow pellets
UP - Unknown precipitation
Name the different Obscurations in a METAR
BR - Mist
FG - Fog
FU - Smoke
VA - Vulcanic ash
DU - Widespread dust
SA - Sand
HZ - Haze
Name the other categorie that can be used in a METAR
PO - Dust/sand whirls
SQ - Squalls
FC - Funnel cloud(s)
SS - Sandstorm
DS - Duststorm
