Initial Flashcards
What is the mix of gases in the atmosphere?
78% Nitrogen
21% Oxygen
1% mix of gases
What are the layers of the Atmosphere?
Troposphere
Tropopause
Stratosphere
Mesosphere
Mesopause
Thermosphere
What is the altitude and temp for the top of the Tropsphere / Tropopause
11km average
8 at the poles
11 mid regions
16 equator
-56.5c
What is the difference between heat and temperature?
Heat is an energy source, measured in Kj or calories
Temperature is the measure of heat in a system.
What is specific heat?
The amount of energy required to raise the temp of 1 kg of mass by 1 C
Water has a higher Specific Heat than Air, which is higher than rock
AKA - ability to store heat
What thermometers are used to measure surface air temp?
Mercury - most common. But Freezes at -38c
Alcohol - freezes at -112c
Bi-metal
Electronic Senors - these need to be calibrated to mercury thermometers on a regular basis
What is a Stevenson box?
A meterology measuring station.
- 1.5 meters of the ground
- Over grassy areas
- protected from direct things such as wind or solar rays
Note: these are usually more accurate in the mornings.
Also don’t measure the air temp on a runway….
How is information gathered for meterology reporting?
abc
Stevenson box
Radiosondes - measures pressure, humidty, temp, wind - attached to a balloon
Satelites
Airtraffic in flight ( both manual and automatic )
Why does temperture matter with regards to the Tropopause?
Temp changes the height of the Tropopause.
How does the sun heat earth?
Sun emits Shortwave radation
It does not heat the lower 10km.
The earth warms up, depending on the surface.
What is Albedo?
The amount of energy reflected back into space.
Conduction vs Convection vs Avection?
Conduciton - warm ground transferring heat into the air.
Convection - rotating hot air and cold air. Usually topped by Cumulus clouds
Avection - sideways movement of air mass ( heat, vapour etc )
What heat does the earth emit?
How is this kept ‘in’?
Long wave radition
Water vapour absorbs the heat.
This means heat coming in from the sun during the day is largely kept at night ( shortware from sun, long wave from earth ).
Greenhouse.
What is inversion?
Where the temp increases with Altitude.
Surface Inversion:
- Polar regions ( ground is cold )
- Valleys and basins, cold air flows down. This causes low level fogs
Avection - warm air is carried from another place.
What is a Isothermal Layer?
Where the temp does not change with altitude.
What is the daily variation ( degrees c ) and why?
Heating is based on heat coming in vs going out.
During the day, solar radition is more than terrestial radition = heating up.
At night, terresterail is more than solar = cooling down.
How does the daily variation change by latitude ( and why )
In the equator - higher daily variation
At the poles - lower daily variation
This is because the solar ration is ‘spreadout’ due to the sloping of the surface.
How does the annual variation change by latitude ( and why )
Equator - only 5 degrees annually
Higher lattitudes = much more variation.
Why?
Due to the tilt of the earth. In winter the solar radtion is much more dispersed.
Why is the annual/daily variation over ocean much lower?
Water has better heat absorbation. This means that more heat is absorved, over a larger area - resulting in little terretial radation.
Why are deserts hotter ( at the same latitude )
Over 50% of solar radition is used for evapouration. In deserts there is less mositure. Resulting in higher temps AND wider variations
What does snow do to temp variations?
Snow reflects more heat AND acts as a blanket. So snowy areas are colder close to the surface and tend to have less variation
What is colder - the Artic or Antarctica ( and why )
Antarctica
In the artic, it’s floating ice - and the water has a moderating effect. Antarctia is a contentiant.
This is also why Siberia is colder than the Artic, despite being closer the equator
What is a Barograph?
A barometer that measures and plots pressure over time.
Usually a Aneroid or Electronic tool.
What are the different types of units to measure pressure ( and conversation factors )
hectopascal ( hPa ) = 1 millibar (mb )
750 mm Hg
29.53 inches Hg
What is QFE and 2 ways to calculate it?
pressure at a given altitude ( airport ).
1. Take the height, divide by 27 and subract that amont from 1013. ( we are using standard lapse )
2. At the airport adjust the baro knob on the altimeter so that the altitude reads 0
3.
How does the air temp affect the rate in DECREASE of pressure?
Colder air has higher rates of decrease
How does temp. affect the vertical distrances between pressure levels?
Cold air has smaller vertical distances that hot air
What does a pressure ( weather ) chart show?
How often is it updated?
What are the pressure intervals?
Pressure, corrected to MSL
Updated every 3 hours
Pressure intervals are 2 or 4 hPa
What is an isobar?
Points of equal pressure
What are the 6 types of pressure systems?
- Low ( Depression ) - can develop into cylones
- Seconday Low
- Trough - extended low pressure
- High ( Anti cyclone )
- Ridge - extended high pressure
- Col - equal point between two highs and lows
What is the pressure gradient?
Difference in pressure / distance
Shown by isobars being close together
A high pressure gradient usually brings high winds
What is trough?
Elogated parts of low pressure
What is a col?
A neutral area between two ‘High’ pressure areas and two ‘Low’ Pressure areas where the wind is very light or calm.
What is QFF
Estimated pressure at sea level.
This is what is used on a pressure ( weather ) chart
What is an Isotach?
Joining all places with equal windspeed
What is the pressure lapse rate?
1 hPa per 27 feet
Difference and uses for
* QFE setting
* QNH setting
* QNE setting
QFE - makes the altimeter read in feet above the airport. Used in training and some military operations
QNH - normal. Set altimeter so that the altitude reads airport elevation
QNE - for use above transistion altitude (13,000 ft to FL150
With Wind, what is veering and backing?
- Veering - wind changing direction in a clockwise manner
-
Backing - anti clockwise direction
*
How is wind strength shown on a chart?
- 1/2 rod = 5 kts
- 1 rod = 10 kts
- 1 triangle = 50 kts
*
What causes gusts and lulls, and when do they happen?
Near the ground
Ground Features
Difference in radition aborbisation
How is wind measured?
And pros and cons
The name of the ground based instrument
Anometer
Place in the open 10m off the ground
Does not measure gusts well, slow to react
What is a an Anemograph?
What is the average time that wind is measured over?
Measures winds and plots it on a graph
Not good in light winds
2 - 10 minutes
How are upper winds measured ( 3 ways ) AND put on a chart?
- Balloons
- Satelites ( looking at movement of water features, such as clouds )
- Aircraft reports
They are put on a chart at a given flight level
In a Metar what does VRB mean in the wind section?
E.G
METAR NZAR 060600Z AUTO VRB10KT // 24/17 Q1018
The wind direction can not be established.