Applying Knowledge of Light and Heat Energy to Local Weather

Energy is coming to us from the sun in the form of light. What happens when light from the sun shines on the earth?

• Some gets reflected. Some absorbed.
  

Use light sensor to compare reflection from water and sand. (water reflects more than sand). Use digital thermometers to measure temperature change of equal masses of room temperature water and room temperature sand.

• Graph over 10 minutes: What is happening here?
• Observations: Reflection of light with light sensor: Sand reflects less light than water; Water reflects more light than sand
• Change in temperature when equal masses placed under lamp for equal time period: PUT TEMPERATURE PROBE NEAR TOP OF SAND. Sand heats up much quicker than water
• Inference: energy to change the temperature of 1 gram of sand by 1 degree Celsius is much less than energy need to change the temperature of 1 gram of water by 1 degree Celsius; that is specific heat of sand, csand is « specific heat of water, cwater
• Heat gained by the sand: ms c s ∆Ts
• Heat gained by the water: mw cw ∆Tw
  

If under the same lamp for the same amount of time, with the same mass and same surface area, and getting the same amount of light energy shining from the lamp on the surface, but sand reflects less light and therefore absorbed more of the energy, AND takes less energy to change the temperature of the sand by one degree AND it conducts thermal energy less quickly then water, all of these contribute to the temperature of the sand NEAR THE TOP OF THE CUP OF SAND increasing more than the temperature of the water in the same amount of time.

What are implications for weather on our Earth?

• Late afternoon: Sea breezes:
• Air above hot sand, hot air is less dense, rises
• Air above cool water, cool, more dense, sinks
• Cool air moves toward land as hot air rises
  

Helpful website: http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/fw/sea/htg.rxml

• Cool air from over the ocean brings in moisture
• The moisture stays with the warm air as it rise and forms clouds over land
  

Helpful website: http://www.usatoday.com/weather/wseabrze.htm