Section 4: Atmospheric and Surface Energy Balances

SLOs: insolation and albedo, greenhouse effect, urban heat island.


Lesson 1:

Instruction

The input and output of solar radiation within the troposphere is the same thing as energy gained and lost by Earth's surface and Earth's atmosphere.  There are multiple types of solar input and output, also called transmission.  Transmission is simply the the passage of shortwave radiation by input and longwave radiation by output.  Insolation is the input of solar radiation when energy is intercepted by Earth.  There are a number of factors that can change the insolation, including reflection of energy back to space.  This reflection is determined by the albedo (a surface's reflective quality).  Surfaces that are light seem to be more reflective than surfaces that are dark.  Clouds, which are light in color, are therefore very reflective, absorb less energy, and have high albedo.  Asphalts, which are dark in color, are not very reflective, absorb more energy, and have low albedo.  For reference, absorption is just the assimilation and conversion of energy from one form to another.             

Photos and Images

 (a surface with high albedo)    (a surface with low albedo)

Quiz

Name 3 surfaces found in Ventura County that have fairly high albedos.  Likewise, name 3 surfaces found in Ventura County that have fairly low albedos.   

 


Lesson 2:

Instruction

Earth has an energy balance, or the total amount of energy input and the total amount of energy output.  Many factors influence this balance, but one warming effect in particular is very important: the greenhouse effect.  Earth naturally emits radiation back into space, moderating the temperatures (and climates) on the planet. However, some of the "greenhouse gases" located in the troposphere, such as carbon dioxide, methane, nitrous oxide, water vapor, and CFCs, reabsorb the outgoing radiation from Earth and trap the heat in Earth's lower atmosphere.  Some of these gases occur naturally (such as water vapor), others are anthropogenic or human-induced (such as CFCs), and a few can be from both natural and anthropogenic sources (such as carbon dioxide).  

Photos and Images

 
 (Earth-atmosphere energy balance)

Quiz

Many global climate and weather patterns are changing because of the greenhouse effect.  Can you name a change in climate or weather because of increasing temperatures that you have noticed in Ventura County?   

 


Lesson 3:

Instruction

The urban environments, the cities and towns of Ventura County, are especially susceptible to creating and trapping heat energy; many surfaces are dark in color, irregular shapes that affect radiation and winds are prominent, building and paving leads to decreased water in the soils, dynamic human activities like the use of electricity alter heat characteristics, and increased air pollution increases energy transfers and stimulates atmospheric water vapor.  All these physical factors influence insolation, wind movements, and dust domes in a city.  This results in urban heat islands, where the cities are warmer than the surrounding landscapes.           

Photos and Images
   (urban heat island: Simi Valley)       (urban heat island: Thousand Oaks)      

Quiz

Listed are some suggestions for reducing urban heat islands in cities: include more open spaces within the urban landscape, repave roads with lighter-colored materials that allow the passage of water to the soil beneath, build structures with reflective roofs, carpool or use public transportation to reduce pollution from automobile exhaust, conserve electricity at all times, so on and so forth.  Ventura County is a special place to live.  To keep our environment healthy we all must attempt to cut down on the things that harm our environment (like the effects of urban heat islands).  Whatever your place in life, you can do something to help.  No matter where you live, I encourage you to plant a tree in your front yard this weekend, carpool one day next week, or turn the lights off in every room of your house that are not in use tonight.  Your assignment is to reduce your personal energy output today, tomorrow, and in the future.             


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2006 Jessica Douglas