1 / 22

Temperature

Temperature. Temperature=average KE of molecules , or average speed of molecules:. Warm air is less dense, cool air is more dense. Temperature Scales. Kelvin scale. Based on absolute zero—temperature at which all motion stops -273 o C= -459 o F= 0 o K Centigrade (Celsius)

kinsey
Télécharger la présentation

Temperature

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. Temperature • Temperature=average KE of molecules, or average speed of molecules: Warm air is less dense, cool air is more dense

  2. Temperature Scales • Kelvin scale. Based on absolute zero—temperature at which all motion stops • -273o C= -459o F= 0o K • Centigrade (Celsius) • Water freezes at 0oC and boils at 100oC • Fahrenheit • Water freezes at 32oF and boils at 212oF…. • Converting oC to oF: Double the C temperature and then add 30…close ‘nuff most of the time oC*1.8 + 32=oF

  3. Influences on Temperature • Latitude • Altitude • Atmospheric circulation • Contrasts between land and water • Warm and cold ocean currents • Local impacts on temperature

  4. Isotherms: Lines of equal temperature

  5. Latitude Land/water distribution Ocean currents Elevation

  6. Daily temperatures • When solar energy in > longwave energy out—temperature rises • Maximum occurs in late afternoon...clouds, haze, humidity, and ground cover control timing and maximum value Radiational Cooling Solar Heating

  7. Daily Temperature Variations • Daytime warming—begins as conduction in layer nearest warm ground • On a calm day, convection can’t influence the lowest portion of the air—can get temperature profile like this:

  8. Effects of winds on lower atmospheric temperatures • Wind causes “forced convection”—much more efficient vertical transfer of heat

  9. Day – Night Radiation Differences • During day, the absorption gain from the sun’s short wave radiation is greater than the earth’s long wave radiation loss, so temperature rises. • During night, the earth’s long wave radiation loss is greater, so temperature falls.

  10. Radiation Inversion • Air temperature usually decreases with height (lapse rate) • At night, ground cools, and air near ground can become much cooler than air above—radiation inversion forms • Temperature increases with height—usually not much higher than 300 feet above the ground • Extremely stable conditions —fog often forms as air reaches Dew Point temperature • Long nights, calm winds, dry and cloud-free atmosphere are most favorable conditions for inversion formation

  11. Formation of Radiation Inversion

  12. Forecast: Cooler or Warmer?? • Daytime: Coastal city vs. Inland city? • Nighttime: Coastal city vs. Inland city? • Daytime: city with clear skies vs. city with cloudy skies • Nighttime: city with clear skies vs. city with cloudy skies • Daytime: city at 6,000ft vs. city at sea level • Nighttime: city at 300ft vs. city at sea level

  13. Atmospheric Influences on Insolation • Absorption • Reflection & Scattering • Transmission

  14. Absorption Atmospheric gases, particulates, and droplets all reduce the intensity of solar Radiation EFFECTS • The absorber gains energy and warms • The amount of energy delivered to the surface is reduced

  15. Reflection Reflection: radiation is redirected away from the surface without being absorbed Albedo: The percentage of visible light reflected • TWO TYPES: • Specular Reflection • Diffuse Reflection

  16. Scattering Disperse radiation in different directions 3 TYPES • Rayleigh • Mie • Nonselective

  17. Rayleigh Scattering Disperse radiation both forward and backward • Leads to blue skies on a clear day • The redness of sunsets and sunrises

  18. Mie Scattering Disperse radiation predominately forward • Effectively scatters all wavelengths therefore sky looks gray • Causes sunrises to be redder

  19. Nonselective Scattering Each wavelength is being refracted a different amount

  20. Transmission When solar radiation enters the atmosphere only a fraction Makes it to the surface

  21. Transmission & The Fate of Solar Radiation • 100 units available at the top of the atmosphere • Atmosphere absorbs 25 units • 7 units are UV radiation absorbed by ozone • Remainder is IR radiation absorbed by gases • Clouds reflect 19 units back to space • Gases and aerosols scatter 6 units back to space • 50 units reach the surface • 5 units scattered back to space

  22. Earth’s Energy Balance Outgoing radiation = Incoming radiation

More Related