Solar Energy to Earth and the Seasons Finish Numerical Modeling Electromagnetic Spectrum Radiation Laws Greenhouse Effect Seasonality Solar Elevation at Noon For Wednesday: Read Ch. 4 (pp )

2015 Peru Summer Study Abroad: Andean Societies and Environments July 6 to July 26, 2015 GHY 1011: Global Climate Change (4 hrs) GHY 3140: Andean Mountain Geography (3 hrs) This 20-day intensive program introduces students to Andean Mountain Geography and Climate and Tropical Glaciers through direct field experience and research activities, readings, discussions, and meetings with guest speakers. Field excursions to Machu Picchu and other locations in the Sacred Valley and an 8-day trek in the Cordillera Vilcanota (with strenuous ascents to over 17,000 ft) will provide an outstanding setting for the study of Andean human-environment interactions and the impacts of climate variability and change on tropical glaciers, ecosystems, and human populations. Program Leaders: Dr. Baker Perry, Mrs. Patience Perry, and Dr. Anton Seimon Interested? Contact Dr. Perry to apply or for more

Numerical Weather Prediction We will keep a close eye on the numerical forecast models, including the Global Forecast System (GFS) model run by the National Centers for Environmental Prediction (NCEP): We will keep a close eye on the numerical forecast models, including the Global Forecast System (GFS) model run by the National Centers for Environmental Prediction (NCEP): Specifically, we will look at the 850 mb temperature (equivalent to ~4750 ft asl or the top of Rich Mountain), mean sea level pressure, and quantitative precipitation forecast (850temp_mslp_precip).Specifically, we will look at the 850 mb temperature (equivalent to ~4750 ft asl or the top of Rich Mountain), mean sea level pressure, and quantitative precipitation forecast (850temp_mslp_precip).

© AMS4 Modeling Earth’s Climate System Short-Term Climate Forecasting Short-Term Climate Forecasting NCEP’s Climate Prediction CenterNCEP’s Climate Prediction Center 30-day (monthly), 90-day (seasonal), and multi-seasonal climate outlooks prepared30-day (monthly), 90-day (seasonal), and multi-seasonal climate outlooks prepared Outlooks issued two weeks to 12.5 months in advance for the coterminous U.S., Hawaii, and other Pacific islandsOutlooks issued two weeks to 12.5 months in advance for the coterminous U.S., Hawaii, and other Pacific islands

Climate Prediction Center

© AMS6 Modeling Earth’s Climate System Long-Term Climate Forecasting Long-Term Climate Forecasting Global Climate Model (GCM): simulates Earth’s climate systemGlobal Climate Model (GCM): simulates Earth’s climate system Numerical models Numerical models Boundary conditions can be changed to determine how Earth adjusts to new conditions Boundary conditions can be changed to determine how Earth adjusts to new conditions

The Electromagnetic Spectrum Figure 2.6

Wavelength and Frequency Figure 2.5

The relationship between the wavelength,, and frequency,, of electromagnetic radiation is based on the following formula, where c is the speed of light: Wave Model of Electromagnetic Energy Note that frequency,  nu), is inversely proportional to wavelength,  lambda). The longer the wavelength, the lower the frequency, and vice- versa. Note that frequency,  nu), is inversely proportional to wavelength,  lambda). The longer the wavelength, the lower the frequency, and vice- versa.

The total emitted radiation (M ) from a blackbody is proportional to the fourth power of its absolute temperature. This is known as the Stefan- Boltzmann law and is expressed as: where  is the Stefan-Boltzmann constant, x W m -2 K -4. Thus, the amount of energy emitted by an object such as the Sun or the Earth is a function of its temperature. The total emitted radiation (M ) from a blackbody is proportional to the fourth power of its absolute temperature. This is known as the Stefan- Boltzmann law and is expressed as: where  is the Stefan-Boltzmann constant, x W m -2 K -4. Thus, the amount of energy emitted by an object such as the Sun or the Earth is a function of its temperature. Stefan Boltzmann Law

Wien’s Displacement Law In addition to computing the total amount of energy exiting a theoretical blackbody such as the Sun, we can determine its dominant wavelength ( max ) based on Wien's displacement law: where k is a constant equaling 2898  m K, and T is the absolute temperature in kelvin. Therefore, as the Sun approximates a 6000 K blackbody, its dominant wavelength ( max ) is 0.48  m: In addition to computing the total amount of energy exiting a theoretical blackbody such as the Sun, we can determine its dominant wavelength ( max ) based on Wien's displacement law: where k is a constant equaling 2898  m K, and T is the absolute temperature in kelvin. Therefore, as the Sun approximates a 6000 K blackbody, its dominant wavelength ( max ) is 0.48  m:

Solar vs. Terrestrial Radiation Solar Radiation (Insolation): Short-wave, high intensity, mostly in the visible portion of the EM spectrum. Source is the Sun. Terrestrial Radiation: Long-wave, lower intensity. Source is the Earth and Atmosphere (or Earth- Atmosphere System)

Solar and Terrestrial Energy Figure 2.7

Group Exercise What is the Greenhouse Effect and why is it important?

© AMS15 Outgoing Infrared Radiation  Greenhouse Effect Heating of Earth’s surface and lower atmosphere caused by strong absorption and emission of infrared radiation (IR) by certain atmospheric gases Heating of Earth’s surface and lower atmosphere caused by strong absorption and emission of infrared radiation (IR) by certain atmospheric gases known as greenhouse gasesknown as greenhouse gases Similarity in radiational properties between atmospheric gases and the glass or plastic glazing of a greenhouse is the origin of the term greenhouse effect Similarity in radiational properties between atmospheric gases and the glass or plastic glazing of a greenhouse is the origin of the term greenhouse effect

© AMS16 Outgoing Infrared Radiation  Greenhouse Effect Responsible for considerable warming of Earth’s surface and lower atmosphere Responsible for considerable warming of Earth’s surface and lower atmosphere Earth would be too cold without it to support most forms of plant and animal life Earth would be too cold without it to support most forms of plant and animal life

© AMS17 Outgoing Infrared Radiation  Greenhouse Gases Water Vapor is the principal greenhouse gas Water Vapor is the principal greenhouse gas Clear-sky contribution of 60%Clear-sky contribution of 60% Other contributing gases: Other contributing gases: carbon dioxide (26%)carbon dioxide (26%) ozone (8%)ozone (8%) methane plus nitrous oxide (6%)methane plus nitrous oxide (6%)

© AMS18 Outgoing Infrared Radiation  Greenhouse Gases Atmospheric window: range of wavelengths over which little or no radiation is absorbed Atmospheric window: range of wavelengths over which little or no radiation is absorbed Visible atmospheric window extendsVisible atmospheric window extends from about 0.3 to 0.7 micrometers from about 0.3 to 0.7 micrometers Infrared atmospheric window fromInfrared atmospheric window from about 8 to 13 micrometers about 8 to 13 micrometers

© AMS19 Outgoing Infrared Radiation  Greenhouse Gases Water vapor strongly absorbs outgoing IR and emits IR back towards Earth’s surface Water vapor strongly absorbs outgoing IR and emits IR back towards Earth’s surface Does not instigate warming or cooling trends in climateDoes not instigate warming or cooling trends in climate Role in climate change is to amplify rather than to trigger temperature trendsRole in climate change is to amplify rather than to trigger temperature trends Clouds affect climate in two ways: Clouds affect climate in two ways: Warm Earth’s surface by absorbing and emitting IRWarm Earth’s surface by absorbing and emitting IR Cool Earth’s surface by reflecting solar radiationCool Earth’s surface by reflecting solar radiation

Figure 2.9

Seasonality Why is seasonality important?

Seasonality Two important seasonal changes Sun’s altitude – angle above horizon or Solar Elevation at Noon (SEN) Day length

Reasons for Seasons Revolution Earth revolves around the Sun Voyage takes one year Earth’s speed is 107,280 kmph (66,660 mph) Rotation Earth rotates on its axis once every 24 hours Rotational velocity at equator is 1674 kmph (1041 mph)

Revolution and Rotation Figure 2.13

Annual March of the Seasons Winter solstice – December 21 or 22 Subsolar point Tropic of Capricorn Spring equinox – March 20 or 21 Subsolar point Equator Summer solstice – June 20 or 21 Subsolar point Tropic of Cancer Fall equinox – September 22 or 23 Subsolar point Equator

Annual March of the Seasons Figure 2.15

11:30 P.M. in the Antarctic Figure 2.16

Insolation at Top of Atmosphere Figure 2.10

Solar Elevation at Noon Figure 2.18

Solar Elevation at Noon (SEN) SEN is the angle of the noon sun above the horizon SEN is the angle of the noon sun above the horizon SEN = 90˚ - ArcDistance SEN = 90˚ - ArcDistance ArcDistance = number of degrees of latitude between location of interest and sun’s noontime vertical rays ArcDistance = number of degrees of latitude between location of interest and sun’s noontime vertical rays If the latitude of location of interest and sun are in opposite hemispheres, add to get ArcDistance If the latitude of location of interest and sun are in opposite hemispheres, add to get ArcDistance If they are in the same hemisphere, subtract from the larger of the two values If they are in the same hemisphere, subtract from the larger of the two values

SEN Example What is the SEN on June 21 for Boone (36 N) What is the SEN on June 21 for Boone (36 N) SEN = 90 – ArcDistance SEN = 90 – ArcDistance Where are the sun’s noontime vertical rays? Where are the sun’s noontime vertical rays? ArcDistance = 36 – 23.5 ArcDistance = 36 – 23.5 ArcDistance = 12.5 ArcDistance = 12.5 SEN = 90 – 12.5 SEN = 90 – 12.5 SEN = 77.5˚ SEN = 77.5˚

Analemma