Describe the effect of latitude on the distribution of incoming solar radiation.
Latitude has the effect of allowing more or less solar radiation to reach the Earth’s surface; the closer the location is to the Equator, the more radiation is allowed to pass through the atmosphere to the Earth’s surface.
This is due to the sun being directly over the Earth’s surface, and not having to travel as far or pass through as much ozone.
Explain the effect of solar and terrestrial radiation on the air temperature.
Long wave radiation and solar radiation that is emitted by the Earth back into the atmosphere. Most of it is absorbed by the water vapor in the atmosphere, which in turn raises the ambient temperature.
The warm earth’s surface warms air particles in touch with the surface through conduction
The warmed air particles rise and through convection they warm higher layers of air
The atmosphere is warmed mainly from below and generally air temperature decreases with a gain in height
Describe the elements that influence the escape of terrestrial radiation.
The following elements influence the escape of terrestrial radiation:
water vapour
water droplets
carbon dioxide
man made pollutants
Explain what is meant by terrestrial radiation.
Terrestrial radiation is the long-wave radiation that is emitted by the earth back into the atmosphere. Most of it is absorbed by the water vapor in the atmosphere
Describe the elements that influence the amount of incoming solar radiation.
Ozone is the gas in the atmosphere, that protects us and influences the amount of Ultraviolet and X ray solar radiation reaching the Earths surface.
Clouds, dust and water vapour also help in influencing the amount of incoming solar radiation.
Explain what is meant by solar radiation.
Solar radiation is the energy given off by the sun.
Solar radiation includes ultraviolet radiation, X Rays and visible light
Explain the importance of correct subscale setting.
If a depression is moving overhead, the altimeter needle will read at a higher altitude even though the aircraft has not moved and the subscale setting has not been altered
The reverse works just as well
ie – the subscale knob function is to allow the correct QNH to be set in the subscale window so the altimeter can read correctly with reference to sea level on any given day.
Explain why an altimeter requires a subscale adjustment.
Altimeters in aircraft contain one or more aneroid capsules which expand as pressure around the aircraft reduces and contracts as the pressure increases or decreases.
As the ambient pressure changes every day, there is a need to adjust the strength or setting of the leaf spring, so that when sea level pressure does changes the altimeter can be adjusted so it continues to read correctly.
Define: a) QNH; b) QFE; c) altitude; d) height; e) pressure altitude.
QNH stands for the atmospheric Pressure at Mean Sea Level.
A common mnemonic for QNH is “Nautical Height” or “Nil Height”
Or QNH as “Query Newlyn Harbour”. Newlyn Harbour in Cornwall, UK is home to the National Tidal and Sea Level Facility which is a reference for mean sea level.
QFE stands for Atmospheric Pressure at Field Elevation “Query Field Elevation” or “Fixed Elevation”
Aviation altitude is measured using Mean Sea Level (MSL) which gives us a height above mean sea level, or altitude.
Height is normally measured above the Ground. It is our altitude taken above a fixed datum (normally the elevation of the surrounding terrain)
Pressure Altitude is the air pressure in terms of altitude in the International Standard Atmosphere
or elevation above a standard datum with the air-pressure of 1013 hPa; also called QNE
Explain how deviation from ISA values influences performance of aircraft and their engines.
When conditions do not meet ISA (which they rarely do) the aircraft will perform differently.
For the ideal conditions for max performance of the aircraft and engines, we want a high pressure coupled with a low temperature.
The lower the temperature and the higher the pressure, the better the performance.