Energy From the Sun

Questions What is the ultimate dource of energy for our planet? How does that energy get to Earth? How does that energy move around on Earth?

Convection Convection is the mechanism of heat transfer in which highly energetic molecules move from one place to another. Ex. Water at the bottom of the skillet receives thermal energy by conduction. The water expands as it warms, becoming less dense. The less dense water rises and denser, cooler water moves down to take its place. This movement creates convection currents

Conduction Conduction is the mechanism of heat transfer in which highly energetic atoms or molecules collide with less energetic atoms or molecules, giving them some energy. Ex. The atoms of a stove-top element moving very rapidly and colliding with the atoms of a skillet, giving thermal energy to the skillet

Radiation Radiation is the mechanism of heat transfer in which atoms or molecules emit electromagnetic waves. These waves carry energy through space and deposit it only when they interact with some other form of matter. Ex. If you hold your hand over the element of the stove you can feel the radiant energy from the element. The energy is converted to thermal energy when it interacts with the hand

Solar Radiation Radiant energy takes the form of electromagnetic rays. These rays can have a wide variety of wavelengths, but the electromagnetic waves that carry radiant energy from the Sun to the Earth contain a very narrow range of wavelengths. The ultraviolet radiation reaching the earth takes the form of visible light

Solar Radiation Cont’d Because space contains very little matter, the solar energy that arrives at Earth’s outer atmosphere is essentially the same as it was when it left the Sun. The amount of energy that reaches the Earth’s outer atmosphere is described as the Earth’s solar constant. The solar constant is the amount of radiant energy that hits 1 m2 of the Earth’s outer atmosphere (at a perpendicular angle) every second.

The Greenhouse Effect The Greenhouse effect is the natural process by which the Earth’s Atmosphere traps heat for a period of time, allowing it to stay at a relatively constant temperature worldwide (15 C)

Greenhouse Gases Greenhouse gases are gases in the Earth’s atmosphere which store thermal energy for a period of time causing the greenhouse effect. The most common greenhouse gases are: Carbon dioxide Methane Water vapour Nitrous oxide ozone

The Enhanced Greenhouse Effect This is an unnatural, human influenced phenomena whereby human activities cause an increase in the amount of greenhouse gases in our atmosphere This causes the atmosphere to hold in more thermal energy than it otherwise would This leads to an increase in the temperature within our atmosphere = GLOBAL WARMING AND SUBSEQUENT CLIMATE CHANGE

Human Activities Leading to the Enhanced Greenhouse Effect The major human contribution to global warming is carbon dioxide emmissions Anytime we burn a fossil fuel to release energy we release carbon dioxide into the atmosphere Fossil fuels are fuels humans combust to generate energy which contain carbon Common fossil fuels Gasoline Oil Coal Natural gas

Other Human Activities Humans also cut down large areas of forests which would naturally take carbon out of the atmosphere

Global Warming Global warming is an increase in the average temperature of the Earth’s atmosphere due to the enhanced greenhouse effect Minor changes in temperature can have dramatic implications for our planet

Effects of global warming Climate change Melting of polar ice caps Glacial retreat Sea level rise Species extinction Changing of agricultural patterns Tropical disease Seasonal pattern changes Drought Increased severe weather events Human displacement Habitat loss Economic disaster

Manitoba Example

Myths

Solutions We’ve all heard of ways to stop global warming It comes down to reducing carbon emissions into the atmosphere Humans will always require energy, so we must find “greener” technologies (technology’s which generate energy without emmiting carbon) and be smarter about how we use energy