controls of temperature
DESCRIPTION
Controls of temperature. Theoretical constructs and models in science. Science uses idealized constructs unlikely to ever occur as a way to make comparisons and infer mechanisms Models are similar: they are simplifications that are used to convey the essence of a concept or process. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/1.jpg)
Controls of temperature
![Page 2: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/2.jpg)
![Page 3: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/3.jpg)
Theoretical constructs and models in science
• Science uses idealized constructs unlikely to ever occur as a way to make comparisons and infer mechanisms
• Models are similar: they are simplifications that are used to convey the essence of a concept or process
![Page 4: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/4.jpg)
![Page 5: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/5.jpg)
![Page 6: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/6.jpg)
Blackbodies
• Any object that is a perfect absorber of all radiation that strikes it and a perfect emitter of this radiation at its given temperature
• No substances in nature are true blackbodies, but only approximations of them
• Terrestrial surface of Earth approximates a blackbody in that it absorbs sunlight and reemits it as infrared radition
![Page 7: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/7.jpg)
Blackbodies
• Radiative equilibrium: when rate of absorption = rate of emission
• Theoretical temperature at radiative equilibrium for Earth is 0 degrees F.
• Observed temp: 59 degrees F• Reason: atmosphere is much less a blackbody
than Earth’s surface. The atmosphere is not a black body. It is a selective absorber
![Page 8: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/8.jpg)
Selective absorbers
• Gases that selectively absorb radiation also emit radiation at that same wavelength (Kirchoff’s Law).– Natural and
anthropogenic greenhouse gases
• Water vapor (0-4%) • Carbon dioxide (0.04%)
![Page 9: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/9.jpg)
Selective absorbers
• Water vapor and carbon dioxide– Strong absorbers of infrared radiation, ie
longwave radition (LW)• Absorption of LW results in molecular motion and
transference of kinetic energy to other atmospheric molecules (conduction)
– Strong emitters of LW• Radiative transfer of LW to ground
– Thus form a “blanket” of warming in the atmosphere
![Page 10: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/10.jpg)
Atmospheric windows
• Wavelengths between 8-11 micrometers are not absorbed by water vapor nor carbon dioxide
![Page 11: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/11.jpg)
Atmospheric windows
• However, clouds (liquid water droplets), are good absorbers in this range of wavelenths, especially low thick clouds like stratus.
• Cloud bases radiate LW downward and block incoming shortwave
• Temperature ranges are smaller with stratus deck– Higher nighttime temps and lower daytime temps
![Page 12: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/12.jpg)
• Sum of atmospheric and surface properties that determine net radiation balance
Radiative forcing at the global scale
![Page 13: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/13.jpg)
• Determined by:– Radiative forcing – Water availability– Sensible heat content– Latent heat transfer– Advective heat
transport
Temp controls at any single point
![Page 14: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/14.jpg)
• Geographic factors are more contingent, variable over time and/or space
Other controls on temp
![Page 15: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/15.jpg)
Temp controls : geographic factors
![Page 16: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/16.jpg)
What explains the packed isotherms and rapid decrease in temperatures at this location?
Temp controls : geographic factors
![Page 17: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/17.jpg)
![Page 18: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/18.jpg)
Altitude
• As elevation increases, temperatures are cooler• Higher altitude: lower air pressure: fewer
molecules to absorb LW radiation (i.e. more radiative cooling
![Page 19: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/19.jpg)
Why are there large annual temperature ranges over interior Canada and Asia?
![Page 20: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/20.jpg)
How would the annual temperature for Vancouver and Winnipegdiffer?
![Page 21: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/21.jpg)
Why is it cooler in south Florida?
![Page 22: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/22.jpg)
Geographic location relative to sea and water
• Maritime effect – Applies to locations near large bodies of water– Smaller temperature range
• Continentality– Applies to locations distant from large bodies of
water (i.e., landlocked)– Larger temperature range (Siberia: -70 F to 70 F
annually)
![Page 23: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/23.jpg)
Water buffers temperature extremes because it heats up and cools down more slowly than land.
![Page 24: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/24.jpg)
Which hemisphere has the lower average annual temperature?
![Page 25: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/25.jpg)
Cloud coverage
• Cloudy conditions predominate: small temperature range
• Clear conditions predominate: larger temperature range
• Cloud type important– Stratus type clouds promote more cooling and
smaller temperature range– Cirrus clouds promote warming
![Page 26: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/26.jpg)
Cloud coverage
![Page 27: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/27.jpg)
Proximity to ocean currents
Cold currents stabilize the atmosphere. Warm currents destablize the atmosphere
![Page 28: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/28.jpg)
Trends in temperature depend upon scale
• Different trends in temperature develop at different temporal (time) scales
![Page 29: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/29.jpg)
![Page 30: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/30.jpg)
Fallacies of scale
• Individualistic fallacy: extrapolating to the broad scale based on observations conducted at small, local scales
• Ecological fallacy: making local-scale characterizations based on broad-scale observations.
![Page 31: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/31.jpg)
What is the normal temperature?
• 30 year average is standard• What would be a record setting high or low
temperature depends upon the length of the record you have available.
• Temperatures are often referenced to their departure from a climatic normal. Again, the length of the record that provided the average determines the amount of departure.
![Page 32: Controls of temperature](https://reader036.vdocuments.us/reader036/viewer/2022062305/56816755550346895ddc0ab2/html5/thumbnails/32.jpg)