# What happens to solar energy ? 1.Absorption (absorptivity=  ) Results in conduction, convection and long-wave emission 2.Transmission (transmissivity=

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What happens to solar energy ? 1.Absorption (absorptivity=  ) Results in conduction, convection and long-wave emission 2.Transmission (transmissivity=  ) 3.Reflection (reflectivity=  )  +  +  = 1

Response varies with the surface type Snow reflects 40 to 95% of solar energy and requires a phase change to increase above 0°C Forests and oceans absorb more than dry lands Then why do dry lands still “heat up” more? Oceans transmit solar energy and have a high heat capacity

Characteristics of Radiation Energy due to rapid oscillations of electromagnetic fields, transferred by photons The energy of a photon is equal to Planck’s constant, multiplied by the speed of light, divided by the wavelength All bodies above 0 K emit radiation Black body emits maximum possible radiation per unit area. Emissivity,  = 1.0 All bodies have an emissivity between 0 and 1 E = hv

Stefan-Boltzmann Law As the temperature of an object increases, more radiation is emitted each second

Temperature determines E, emitted Higher frequencies (shorter wavelengths) are emitted from bodies at a higher temperature Max Planck determined a characteristic emission curve whose shape is retained for radiation at 6000 K (Sun) and 300 K (Earth) Energy emitted =  (T 0 ) 4 Radiant flux or flux density refers to the rate of flow of radiation per unit area (eg., W  m -2 ) Irradiance=incident radiant flux density Emittance =emitted radiant flux density

Wien’s Displacement Law As the temperature of a body increases, so does the total energy and the proportion of shorter wavelengths max = (2.88 x 10 -3 )/(T 0 ) *wavelength in metres Sun’s max = 0.48  m Ultraviolet to infrared - 99% short-wave (0.15 to 3.0  m) Earth’s max = 10  m Infrared - 99% longwave (3.0 to 100  m)

8-11  m window

ALBEDO: April, 2002 White and red are high albedo, green and yellow are low albedo

white snow0.80-0.95 old snow0.40-0.60 vegetation0.15-0.30 light colour soil0.25-0.40 dark colour soil0.10 clouds0.50-0.90 calm water 0.10 (noon) March 3, 2009

DAYTIME: Q* = K  - K  + L  - L  Q* = K* + L* NIGHT: Q* = L* K = solar (shortwave) radiation ↓ = incoming L = longwave (terrestrial radiation)↑ = outgoing Q* = net all-wave radiation* = net Radiation Balance

Source: NOAA L

Conduction The transfer of heat from molecule to molecule within a substance

Convection and Thermals

Convection The transfer of heat by the mass movement of a substance (eg. air) Rising air expands and cools Sinking air is compressed and warms

The Hydrological Cycle

Heat capacity The amount of heat energy absorbed (or released) by unit volume of a substance for a corresponding temperature rise (or fall) of 1 °C Specific heat The amount of heat energy absorbed (or released) by unit mass of a substance for a corresponding temperature rise (or fall) of 1 °C

Latent heat The heat energy required to change a substance from one state to another Sensible heat Heat energy that we can feel and sense with a thermometer

Thermometer and radiation shield SENSIBLE HEAT Radiation Sensors (PAR and K  ) Raingauge Datalogger Photo: Weather station, Tausa, Cundinamarca, Colombia (3,243 m asl)

http://www.jgiesen.de/sunshine/index.htm Check this out:

N

Dec 15, 2004 Jan 19, 2005 Temperature (  C)

Dec 15, 2004 Jan 19, 2005

Dec 15, 2004Jan 19, 2005 Temperature (  C)

10 – 100  m ●

0.0001 – 0.001  m ●

Mie scattering 0.01 to 1.0  m ●

LONG PATH LENGTH OF LIGHT THROUGH THE EARTH’S ATMOSPHERE MOST OF THE THE VIOLET, BLUE AND GREEN LIGHT IS SCATTERED

(from Pacific) (prairie cold)

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