{ Energy “The ability to do work” “The ability to do work”

Energy can be found in a number of different forms. It can be:  chemical energy,  electrical energy,  heat (thermal energy),  light (radiant energy),  mechanical energy, and  nuclear energy. “Energy Is the Ability to Do Work. “

Energy makes everything happen and can be divided into two types:   Stored energy is called potential energy.   Moving energy is called kinetic energy. Stored and Moving Energy

 Energy is measured in many ways.  Energy also can be measured in joules.  The term "joule" is named after an English scientist James Prescott Joule who lived from 1818 to James Prescott JouleJames Prescott Joule  He discovered that heat is a type of energy. How Do We Measure Energy?

“One joule is the amount of energy needed to raise the temperature of one gram of water one degree Celsius.” Like in the metric system, you can have kilojoules -- "kilo" means 1,000. 1,000 joules = 1 kilojoule

A piece of buttered toast contains about 315 kilojoules (315,000 joules) of energy. With that energy you could:  Jog for 6 minutes  Bicycle for 10 minutes  Walk briskly for 15 minutes  Sleep for 1-1/2 hours  Run a car for 7 seconds at 80 kilometres per hour (about 50 miles per hour)  Light a 60-watt light bulb for 1-1/2 hours

Energy can be transformed into another sort of energy. It cannot be created AND it cannot be destroyed. Energy has always existed in one form or another. Changing Energy

1. Conduction 2. Convection 3. Radiation Three Mechanisms of Energy Transfer

Conduction occurs when energy is passed directly from one item to another. Highly energetic molecules collide with less energetic molecules, giving them some energy Conduction

Ex: Heat element (highly energetic molecules) transfers energy to skillet ( less energetic molecules ) Only energy is transferred, molecules do not move from one object to another

 Highly energetic molecules move from one place to another  Convection is the movement of gases or liquids from a cooler spot to a warmer spot.  Ex: Water molecules in a pot receive energy by conduction at bottom of pot. Water expands and rises (less dense) and cooler water sinks (more dense) moving in a circular path. Convection:

Movement of molecules creates convection currents. The movement is in a circular pattern.

 The sun's light and heat cannot reach us by conduction or convection because space is almost completely empty. There is nothing to transfer the energy from the sun to the earth.  om/c4-uv-e.html om/c4-uv-e.html om/c4-uv-e.htmlRadiation

The sun's rays travel in straight lines called heat rays. When it moves that way, it is called radiation.

 When sunlight hits the earth, its radiation is absorbed or reflected.  Darker surfaces absorb more of the radiation and lighter surfaces reflect the radiation.  So you would be cooler if you wear light or white clothes in the summer.

Radiation: Atoms or molecules emit electromagnetic waves which carry energy through space and transfers it to an object when it interacts with it

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 Ultraviolet radiation is one form of radiant energy coming from the sun.  The ozone layer provides a defence against UV radiation reaching Earth, but several other factors also affect how UV penetrates our atmosphere.  These include: latitude, season, time of day, altitude, cloud cover, rain, land cover and air pollution. Ultraviolet Radiation

 UV-A is the least damaging form of UV radiation and reaches the Earth in greatest quantity. Most UV-A rays pass right through the ozone layer  UV-B radiation is potentially very harmful. Fortunately, most of the surfs UV-B radiation is absorbed by ozone in the stratosphere.  UV-C radiation is potentially the most damaging because it is very energetic. Fortunately, all UV-C is absorbed by oxygen and ozone in the stratosphere and never reaches the Earth's surface. There are three categories of UV radiation.

Exposure to UV-B radiation :   causes skin cancer   hastens skin aging   can cause eye damage   the human immune system can also be weakened by exposure to UV-B HOW DOES UV-B EXPOSURE AFFECT PEOPLE?

 It is Important to know that UV-B radiation has always had these effects on humans.  In recent years, these effects have become more prevalent because Canadians are spending more time in the sun and are exposing more of their skin in the process.  An increase in the levels of UV-B reaching the Earth as a result of ozone depletion may compound the effects that exposure to the sun has already created.

 Excessive UV-B inhibits the growth processes of almost all green plants.  There is concern that ozone depletion may lead to a loss of plant species and reduce global food supply.  UV-B can cause cancer in domestic animals just like it can in humans. DOES UV-B AFFECT PLANTS AND ANIMALS?

 For every bit of sunlight that the Earth receives, an equal amount (on average) of IR radiation must travel from the Earth back to outer space. = Earth’s Energy Budget  Everything emits infrared radiation -- you usually don't notice it, though, because it is weak, and you can't see it like you can sunlight. What is infrared (heat) radiation?

The radiant heat you feel from an oven or a fire is infrared radiation.  Greenhouse gases in the atmosphere, especially water vapour, trap some of this infrared radiation, and keep the earth habitable for life. Greenhouse gases Greenhouse gases

Clouds also trap some of this radiation. The reason why the air cools so quickly on a clear, dry evening is because the lack of humidity and clouds allows large amounts of IR radiation to escape rapidly to outer space.

Method of energy transfer that carries energy to earth? Radiation Why do all life forms on earth depend on solar radiation? Plants convert the energy from the sun into a usable form (carbohydrate) for all living organisms. *No other life forms can use the energy directly from the sun.

 Amount of radiant energy that hits 1m 2 of earth’s outer atmosphere every second  The amount reaching the surface varies considerably based on the time of the year and local weather conditions.  The amount reaching the surface varies considerably based on the time of the year and local weather conditions.  In broad terms:  approximately 30% of the incoming solar energy is reflected  and 20% is absorbed by the atmosphere.  and 20% is absorbed by the atmosphere.  About 50% of the incoming sunlight is available for use at the surface. Define “solar constant”:

Energy from the sun reaches the Earth-atmosphere system in the form of electromagnetic radiation. However, only about half of the solar radiation makes it to the Earth's surface. The rest is either absorbed or reflected by clouds and the atmosphere. The Earth's surface itself can emit infrared radiation. The balance between incoming and outgoing radiation is called: The Earth’s Radiation Budget

Absorption: 70% total 16% air 4% clouds 50% earth Reflection: 30% 6% air 20% clouds 4% ground Distribution of Solar Radiation

The earth radiates as much energy as it absorbs. What happens to that energy between the time it is absorbed and the time it is radiated back to space is what drives our weather systems