Unit 8 Earth in Space Solar Energy

Energy From the Sun At Sun’s core: Hydrogen atoms fuse to make helium releasing HUGE amounts of energy Electromagnetic Spectrum: the energy that is radiated from the sun

Energy Multiple nuclei are joined; large amount of energy released; i.e. solar energy A heavy nucleus is split to make smaller nuclei; large amount of energy released; i.e. nuclear power A chemical process where whole atoms recombine; small amount of energy released; i.e. burning fossil fuels Nuclear Fusion Nuclear Fission Combustion

Why do Nuclear Reactions yield so much Energy? Energy released (E) is equal to change in mass (m) times the speed of light (c = 3x108 m/s) E = mc2 Nuclear reactions release so much energy because there is a change in mass. There is NO change in mass in chemical combustion.

Energy occurs in 3 forms: Solar Energy Heat Energy Chemical Energy Solar energy is converted to heat & chemical energy when it reaches Earth Only 50% of all solar energy reaches Earth

Solar Energy (electromagnetic radiation) travels as transverse waves. Frequency (f) = 1 / wavelength (λ) Wavelength Shorter wavelength Higher frequency Higher energy Longer wavelength Lower frequency Lower energy

Radiation from the Sun occurs in different forms identified by wavelength: Gamma Ray Radio Micro wave Visible X Ray UV Infrared

Electromagnetic Spectrum Figure 1

Insolation: The amount of solar energy received on Earth per unit of area per time. The amount received depends on the angle that the electromagnetic wave strikes Earth, which depends on: Time of year Location on Earth

More direct rays lead to more insolation: Polar insolation is less than Equatorial insolation Maximum insolation occurs in the visible light spectrum Greater insolation supports more photosynthesis and more plant growth

Insolation Closer to poles, rays have more angle, rays are more diffuse, insolation is lower Figure 3 At the equator, rays have less angle, rays are more concentrated, insolation is higher

Figure 5 Figure 4 Figure 2