ATPL Temp And Heat Exchange Flashcards
Describe Celsius
0ºC freezing point or melting point of water
100ºC boiling point of water
Named after Anders celsius
Describe Fahrenheit
0 °F = freezing point of a mixture of water, ice, and ammonium chloride (a salt)
•100 °F = best estimate of human body temperature
•Named after Daniel Gabriel Fahrenheit
•32 °F = water freezing 212 °F = water boiling
Describe kelvin (absolute)
SI unit for temperature
•Uses absolute zero as its starting point
•No molecular movement at absolute zero
•Not written as a degree
What are conversion equations for different types of heat
(°F – 32) x 5/9 = °C
•(°C x 9/5) + 32 = °F
•0 K = -273 °C 0 °C = 273 K
What is meant by solar and terrestrial radiation
Solar radiation = electromagnetic radiation emitted from the Sun
•Terrestrial radiation = electromagnetic radiation emitted from Earth
•Radiation is not hot but produces heat on contact
•Net gain of insolation during the day and loss at night
State the wavelength of solar and terrestrial radiation
Solar radiation = 0.4 – 4 μm (micrometre)
•Terrestrial radiation = 4 – 80 μm
Describe the effect of sun angle on the amount of solar radiation received by the earth
- Suns angle at 90° to the Earths surface = maximum radiation received
•Occurs near the equator
•Higher latitudes the angle reduces, spreading the same amount of radiation over a larger area
•Higher latitudes = less heating
Describe the effect of the LENGTH OF DAY on the amount of solar radiation received by the earth
Longer days = more solar radiation received
•Due to the delay of heating air, hottest time of day is mid afternoon
•Longer days also mean shorter nights
Describe the effect of the SEASON on the amount of solar radiation received by the earth
Summer = most solar radiation received
•Winter = lowest amounts of solar radiation received
•Due to Earths tiled rotational axis at 23.5° and elliptical orbit around the sun
Define solstice
Sun reaches most northerly or southerly latitude for the year
•Represents longest and shortest day
•Jun 20th or 21st = shortest day in southern hemisphere
•Dec 21st or 22nd = longest day in Southern Hemisphere
Define equinox
Centre of Sun directly over the equator
•Day will be equal length in northern/southern hemisphere
•Mar 20th and Sep 22nd or 23rd depending on year
State the significance of the solstice
Jun = Sun at most northern latitude (no sunlight at the south pole)
•Dec = Sun at most southern latitude (no sunlight at the north pole)
•Solar radiation for southern hemisphere largest in Sep – Mar
•Lowest from Mar - Sep
What are the reason for seasons
Seasons are caused by the fact that earth is tilted on its axis and does not change through the year. So the northern hemisphere is tilted towards the sun in June and away from it in December.
State the significance of the equinox
Only time when northern and southern hemisphere has equal day length
•Occurs twice a year
