Radiation, Insolation, and Energy Transfer. Solar Radiation: Sun to Earth. Speed of light: 300,000 km/second (186,000 miles/sec.) Distance to Earth: 150 million km (93 million miles) Radiation reaches us in about 8.3 minutes. Radiation.
Solar Constant = 2 calories/cm2/minute
Micrometers or microns (µ) = 1/1 000 000 or 0.000 001 or 10-6
Hence Microwaves are about 1mm - long.Radio waves are about a meter to 1000 meters long.
Sun: 6000ºC (11,000ºF)
Earth: 15ºC (60ºF)
(Wein’s Law) The hotter the radiating body, the shorter the wavelength of maximum radiation.
Scattering (diffuse radiation)
Rayleigh Scattering:selective scattering if dust is about 1/10 the wavelength of light (.5 micron)
VIB G YOR 4x 1x
1. sun appears yellow as VIB is scattered out.
2. sky is blue: VIB is down-scattered and becomes prominent.
Mie Scattering:white scattering, non-selective, occurs with bigger particles, about 30x the wavelengths of light.
1. salt crystals: things whiter at distance2. bluer sky at high elevation - less white 3. white clouds.
Change in direction direction of radiation, by wavelength, in response to change in density of medium.
Molecule to molecule energy transfer
When molecules collide, higher energy molecules excite lower temperature molecules, thereby transferring kinetic (heat) energy.
Heat is transferred by the movement, from place to place, of a gas or liquid. The principal motion is vertical. All heated gases and liquids experience this kind of “mixing” heat exchange.
When air rises it expands and cools as its pressure is decreased. Thus, when it descends, it is warmed, as pressure increases. This change takes place without the addition or subtraction of energy from another source.
22 Latent Heat
19 direct absorb