Planetary Energies

Trevor Craig

Energy Science 110

Planetary Energies, 8

9/21/11           

This lecture was about where energy comes from and how it affects our world. Almost all forms of energy, in one way or another, can be tracked back to the sun. The sun affects our weather, our climate, and how we live. The sun releases 3.89x10^26 J of radiation which is a lot of energy that is being released, much of this radiation comes down to earth. The sun is on a cycle of radiation levels emitting toward our atmosphere, but typically we can say that 1366 W m-2 of radiation is at the edge of the atmosphere, but this number can vary depending on what time of the cycle it is, from 1365.5 W m-2 to about 136.5 W m-2. All of these things play a factor for us on earth.

Now when we hear radiation we typically think of bad things, but actually everything emits radiation, depending on the temperature it has. Humans internal temperature is at 37 C and using Stefan Boltzmans law of E= σT^4, we can find out that the average human emits 8.6 MJ of radiation. In fact, the reason there is a light is because of radiation, the visible color spectrum is a small part of the amount of radiation waves, only being 0.4-0.75 µm. There are many different types of radiation, and all are slightly different.

The amount of radiation that reaches where we live changes as the earth rotates around the sun, which is what causes the seasons like winter and summer. Another thing that affects the amount of radiation that reaches us is the time of day. During the day there is more radiation then at night; clouds have a great effect on the temperature and the amount of radiation that reaches us. From the total amount of radiation that is coming from the sun to earth only 45% of it is reaching the earth’s surface, the other part 55% is mostly stopped from the atmosphere.  

So what makes up the atmosphere and what stops the most amount of radiation? The largest gasses in the atmosphere are Nitrogen at 78.084% and Oxygen at 20.946% and 4^th in abundance is Carbon Dioxide at 0.0383%. Even though carbon dioxide is not very much of the atmosphere it plays a critical part in blocking out radiation. Some radiation comes through the atmosphere and warms the earth. The earth then sends out some of its radiation into the atmosphere, then some of that energy is released into the atmosphere and the rest is reflected off some of the gasses to come back down to the earth and the cycle starts over, this is what we call the greenhouse effect.

Flux-Constant or frequent change; fluctuation.

Solar Flare- A brief powerful eruption of particles and intense electromagnetic radiation from the sun's surface, associated with sunspots and causing disturbances to radio communication on earth.

ENSC110 Planetary Energies 8