1 / 46

Chapter 2 – Solar Radiation and the Seasons

Chapter 2 – Solar Radiation and the Seasons. Energy. Energy is defined as the ability to do work. Energy. Energy is defined as the ability to do work Kinetic energy – the energy of motion. Energy. Energy is defined as the ability to do work Kinetic energy – the energy of motion

archibald
Télécharger la présentation

Chapter 2 – Solar Radiation and the Seasons

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 2 – Solar Radiation and the Seasons

  2. Energy • Energy is defined as the ability to do work

  3. Energy • Energy is defined as the ability to do work • Kinetic energy – the energy of motion

  4. Energy • Energy is defined as the ability to do work • Kinetic energy – the energy of motion • Potential energy – energy that can be used

  5. Energy • Energy is defined as the ability to do work • Kinetic energy – the energy of motion • Potential energy – energy that can be used • Energy is conserved! (1st law of thermodynamics)

  6. Energy Transfer • Although energy is conserved, it can move through the following mechanisms: 1) Conduction – heat transfer by physical contact, from higher to lower temperature

  7. Conduction in the Atmosphere • Occurs at the atmosphere/surface interface • Partly responsible for daytime heating/nighttime cooling! (The diurnal cycle)

  8. Energy Transfer • Although energy is conserved, it can move through the following mechanisms: 2) Convection – heat transfer by movement

  9. Convection in the Atmosphere • Vertical transport of heat

  10. Convection in the Atmosphere • Vertical transport of heat • Horizontal transport of heat = advection

  11. Convection in the Atmosphere Courtesy maltaweather.info

  12. Energy Transfer • Although energy is conserved, it can move through the following mechanisms: 3) Radiation - transfer of energy by electromagnetic radiation (no medium required!)

  13. Radiation Characteristics of radiation 1) Wavelength – the distance between wave crests

  14. Radiation Characteristics of radiation 1) Wavelength – the distance between wave crests 2) Amplitude – the height of the wave

  15. Radiation Characteristics of radiation 1) Wavelength – the distance between wave crests 2) Amplitude – the height of the wave 3) Wave speed – constant! (speed of light - 186,000 miles/second)

  16. Radiation • The wavelength of radiation determines its type

  17. Radiation • The wavelength of radiation determines its type • The amplitude determines the intensity

  18. Radiation • What emits radiation?

  19. Radiation • What emits radiation? EVERYTHING!!

  20. Radiation • The types (wavelengths) and intensity (amplitudes) of radiation depend on temperature

  21. Radiation • The types (wavelengths) and intensity (amplitudes) of radiation depend on temperature Sun is HOT (~10,000oF) Earth is NOT (~59oF) Shortwave radiation Longwave radiation

  22. Radiation • Blackbody – an object that absorbs all radiation and emits the maximum amount of radiation at every wavelength (not realistic)

  23. Radiation • Blackbody – an object that absorbs all radiation and emits the maximum amount of radiation at every wavelength (not realistic) • Graybody – an object that emits a fraction (emissivity) of blackbody radiation (more realistic)

  24. Radiation • Blackbody – an object that absorbs all radiation and emits the maximum amount of radiation at every wavelength (not realistic) • Graybody – an object that emits a fraction (emissivity) of blackbody radiation (more realistic) • Total radiation emitted is equal to the sum over all wavelengths above

  25. Radiation Laws • Stefan-Boltzmann Law – the total amount of blackbody radiation emitted (I) is related to temperature: I = σT4

  26. Radiation Laws • Stefan-Boltzmann Law – the total amount of blackbody radiation emitted (I) is related to temperature: I = σT4 • For a graybody, this becomes: I = εσT4 where ε is the emissivity

  27. Radiation Laws • Wien’s Law – the wavelength of maximum blackbody emission is related to temperature: ʎmax = 2900/T

  28. Radiation Laws • Wien’s Law – the wavelength of maximum blackbody emission is related to temperature: ʎmax = 2900/T Sun is HOT (~6000K) Earth is NOT (~290 K)

  29. Practical use of Radiation Properties • Visible satellite imagery doesn’t work in the dark

  30. Practical use of Radiation Properties • Visible satellite imagery doesn’t work in the dark • Infrared (longwave) radiation occurs always – use infrared satellite imagery!

  31. Solar Radiation and the Earth • The solar constant – the amount of solar radiation hitting the earth

  32. Solar Radiation and the Earth Earth – 1367 W/m2 Mars – 445 W/m2

  33. Solar Radiation and the Earth • Earth orbits the sun eliptically (once per 365.25) days Farthest point (aphelion, Jul 4) Closest point (perihelion, Jan 4)

  34. Solar Radiation and the Earth • Earth gets ~7% more radiation in winter (not enough to cause the seasons!) What does? Farthest point (aphelion, Jul 4) Closest point (perihelion, Jan 4)

  35. Solar Radiation and the Earth • Earth’s tilt is the true cause of the seasons! • Earth’s axis is tilted 23.5o

  36. Solar Radiation and the Earth • 3 factors contribute to the amount of incoming solar radiation (insolation): 1) Period of daylight

  37. Period of Daylight Vernal and autumnal equinox

  38. Period of Daylight Summer solstice

  39. Period of Daylight Winter solstice

  40. Solar Radiation and the Earth • 3 factors contribute to the amount of incoming solar radiation (insolation): 2) Solar angle

  41. Solar Angle

  42. Solar Radiation and the Earth • 3 factors contribute to the amount of incoming solar radiation (insolation): 3) Beam depletion

  43. Beam Depletion

  44. Solar Radiation and the Earth • What’s the end result of these 3 mechanisms and the tilt of the earth?

  45. Solar Radiation and the Earth • What’s the end result of these 3 mechanisms and the tilt of the earth? - Weather as we know it!

  46. Solar Radiation and the Earth • What’s the end result of these 3 mechanisms and the tilt of the earth? - Weather as we know it! Jet stream… Mid-latitude cylcones…fronts… Thunderstorms…winds

More Related