ELECTROMAGNETIC RADIATION Electromagnetic spectrum Shortwave 3 m Longwave
- Slides: 21
ELECTROMAGNETIC RADIATION
Electromagnetic spectrum Shortwave < 3 µm Longwave > 3 µm
Solar (shortwave) : 8% UV, X-ray, Gamma 47% visible 45% infrared Terrestrial (longwave): 100% infrared
λ = wavelength
Atmospheric absorption Gases in atmosphere absorb at different wavelengths. Wavelengths not absorbed are TRANSMITTED.
absorption vs. transmission
Atmospheric absorption/transmittance graph White gaps are “atmospheric windows of transmission”; black areas are absorption bands
Longwave absorption
Shortwave absorbers: • Ozone: absorbs UV < 0. 3 μ • H 2 O vapor : absorbs > 0. 8 μ Atmospheric “window” of transmission: 0. 3 – 0. 8µ (shortwave) Longwave absorbers: • H 2 O vapor, CO 2, ozone, CH 4, N 2 O Another window: 8 – 11 µ (longwave)
Review SOLAR RADIATION: shortwave (visible, UV, IR); higher radiation intensity; absorbed by ozone and water vapor; atmospheric window of transmission : 0. 3 – 0. 8 µ TERRESTRIAL RADIATION longwave (IR); lower radiation intensity; absorbed by “greenhouse gases” (O 3, H 2 O, N 2 O, CO 2, CH 4) atmospheric window of transmission : 8 – 11 µ
Solar constant amount of solar radiation received at top of atmosphere on a plane surface perpendicular to sun’s rays. (not diminished by atmosphere) = 1372 W m-2 1 Watt = 1 J / sec
What is relationship between wavelength and temperature? What is relationship between energy and temperature?
Rules of Radiation 1. Wein’s Law all objects emit energy at wavelengths inversely proportional to their temperature Wein’s Law gives wavelength of peak intensity (λmax) λmax = 2897 / T (temp in Kelvins)
For earth: λmax = 2897 / 300 K = 9. 6 μ (infrared) For sun: λmax = 2897 / 6000 K = 0. 48 μ (visible) For molten lava? (temp = 1073 K) λmax = 2897 / 1073 = 2. 7 μ (shortwave infrared)
2. Stefan-Boltzmann Law E = σ (T 4) (temp in Kelvins) σ = Stefan-Boltzmann constant: 5. 67 x 10 -8 Wm-2 K-4
Humans maintain skin temp of 91°F (306 K). 1. In which portion of the spectrum do we radiate? Wein’s Law: λmax = 2897 / temperature 2. How much energy do we radiate? Stefan-Boltzman : E = σ (T 4) σ = 5. 67 x 10 -8 Wm-2 K-4
- Outgoing longwave radiation
- Olr earth
- Greenhouse effect long and shortwave radiation
- Types of radiation in the electromagnetic spectrum
- Em light spectrum
- N
- Shortwave infrared camera
- D orbital shape
- Absorption spectrum
- Intensity of wave
- When electromagnetic radiation of wavelength 300
- Intensity of electromagnetic wave
- Which telescope detects invisible electromagnetic radiation
- Electromagnetic radiation
- Facts about electromagnetic radiation
- Sound waves are electromagnetic waves. true false
- Electromagnetic spectrum conclusion
- Electromagnetic spectrum
- What is the electromagnetic spectrum
- Electromagnetic spectrum micrometers
- Troop 306
- Chapter 18 the electromagnetic spectrum and light