B. Identify the Sun As the Source of All Energy on Earth

Global Systems

1. Describe how the relationships among input solar energy, output terrestrial energy and energy flow within the biosphere affect the lives of humans and other species

a. explain how climate affects the lives of people and other species, and explain the need to investigate climate change

b. identify the Sun as the source of all energy on Earth

c. analyze, in general terms, the net radiation budget, using per cent; i.e., solar energy input, terrestrial energy output, net radiant energy

d. describe the major characteristics of the atmosphere, the hydrosphere and the lithosphere, and explain their relationship to Earth’s biosphere

e. describe and explain the greenhouse effect, and the role of various gases—including methane, carbon dioxide and water vapour—in determining the scope of the greenhouse effect

Biosphere:

Another name for the surface of the earth; it is composed of all parts that sustain life
It is composed of 3 divisions
The atmosphere: the layer of air around the earth
The hydrosphere: the water (marine and freshwater) on the surface of the earth
The lithosphere: the land surface not covered by water

Atmosphere:

is composed of 78% nitrogen gas, 21% oxygen gas, and less than 1% argon, carbon dioxide, and numerous other gases
is divided into several layers, from the bottom up they are: troposhere, stratosphere, ionosphere, and magnetosphere
the stratosphere (15-50 km) contains the important gas ozone, composed of 3 atoms of oxygen whereas oxygen gas is only 2 atoms of oxygen. The ozone layer is concentrated around 15-30 km above the earths surface
Ozone absorbs harmful UV-b radiation preventing most of this radiation from reaching the surface of the earth. There are 3 types of UV radiation: UV-a is least harmful and not blocked out by the atmosphere, UV-b is more harmful causing skin cancer in increased exposure, and UV-c the most damaging radiation, which is totally blocked out by the upper layers of the atmosphere.
Over the last 40-50 years chloroflorocarbons, produced as a propellant for aerosol cans (spray cans and bottles) has been destroying the ozone layer. UV light in the upper atmosphere decomposes CFC’s releasing the chlorine atom. This atom will react with ozone, breaking ozone into normal oxygen which does not block out the UV-b radiation. In the late 1980’s and international ban on CFC’s has slowly had a levelling off effect on the rate of ozone depletion.

The carbon cycle and the greenhouse effect

Carbon dioxide is produced during fossil fuel combustion
Carbon dioxide allows light to pass through but traps reflected heat. This is the greenhouse effect
The greenhouse effect keeps the earth warm and allows life to exist. But too much carbon dioxide can increase global temp too fast.
This can cause melting of glaciers and icecaps, increasing the level of the ocean, flooding coastal cities, increased storms, hurricanes, tornadoes, and shifts in global weather and climate

Hydrosphere:

Water covers nearly 75% of the surface of the earth
Most of this water is marine, or saltwater.
Of the freshwater the majority is locked as ice in the polar ice caps
water makes up 70-99% of all living things
it is the major compound in living cells
needed for digestion, transport, cooling, location where reactions occur

Lithosphere:

The land mass of the earth covers about 25% of the surface of the earth
Much of this land mass is not liveable by humans (deserts, icecaps, mountain ranges)
The areas of the lithosphere where life exists are divided into regions called Biomes characterized by dominant vegetation and associated animal species.
Two major life sustaining processes occur here, and in the oceans. Photosynthesis and cell respiration. (write chemical reactions)

Energy Flow in Global systems

energy used to sustain life in the biosphere mostly comes in the form of light from the sun.
is generated by fusion reactions in the sun where two hydrogen atoms fuse to form one helium atom. In the process there is a loss of mass. The mass is converted into energy according to Einstein’s famous equation E=mc2
The energy released is in the form of the electromagnetic spectrum (gamma, UV, visible, infrared, radio, TV, )
the sun is too far away to feel any heat, plus the vacuum of space prevents heat from being transmitted through space
the visible light reaches the outer atmosphere and from here down to the earth surface it gets reflected and absorbed by different parts of the biosphere
is reflected by the upper atmosphere, scattered by the atmosphere and clouds, absorbed by the surface, absorbed by oceans and used for wind and waves, absorbed by plants for photosynthesis, reflected by the surface (lithosphere)
Ultimately all energy received by the earth is reradiated back into space in the form of heat. The energy the earth receives over the long term always balances the energy it gives off. This satisfies the first law of thermodynamics. The second law of thermodynamics states that when energy is converted from one form to another the conversion is never 100% efficient. Much of the energy is lost as heat. This is the heat radiated from the atmosphere, lithosphere, and hydrosphere. Overall energy always flow through a system, it drives the system. It may be temporarily stored, and given off later, it may be changed from one form to another, but it is never lost. Energy flows, which in turn causes matter to cycle and life to exist
Examples of conversions that release heat are decomposition and muscle contractions
The suns energy produces life on earth through the processes of photosynthesis and cell respiration. Less than 1% of the energy that reaches the biosphere is used for photosynthesis. This is the energy that is transferred through all food chains and food webs. It is the energy that is inside every cell of every living organism.

2. Analyze the relationships among net solar energy, global energy transfer processes—primarily radiation, convection and hydrologic cycle—and climate.

a. describe, in general terms, how thermal energy is transferred through the atmosphere (i.e., global wind patterns, jet stream, Coriolis effect, weather systems) and through the hydrosphere (i.e., ocean currents, large bodies of water) from latitudes of net radiation surplus to latitudes of net radiation deficit, resulting in a variety of climatic zones

b. investigate and describe, in general terms, the relationships among solar energy reaching Earth’s surface and time of year, angle of inclination, length of daylight, cloud cover, albedo effect and aerosol or particulate distribution

c. explain how thermal energy transfer through the atmosphere and hydrosphere affects climate

d. investigate and interpret how variations in thermal properties of materials can lead to uneven heating and cooling

e. investigate and explain how evaporation, condensation, freezing and melting transfer thermal energy; i.e., use simple calculations of heat of fusion Hfus= n Q and vaporization Hvap= n Q , and Q=mc∆t to convey amounts of thermal energy involved, and link these processes to the hydrologic cycle

The energy that reaches the earth’s surface is not always evenly distributed. Variables such as cloud cover, latitude, and albedo influence the amount of solar radiation that part of the earth receives. This results in differences in weather and climate at different times of the year in different locations.
Latitude - the position on the Earth relative to the equator. The location on the Earth determines the angle of incoming solar radiation and therefore the amount of light absorbed, and heat given off, at that latitude.
The latitude of an area on the earth will also influence how much solar radiation that area receives at different times of the year. The earth is tilted on its axis approximately 23 degrees. As the earth orbits around the sun this tilt causes the northern hemisphere (as compared to the southern hemisphere) to be more exposed to the direct rays of the sun for half of the year and then when the earth is in the opposite side of its orbit the northern hemisphere will be less exposed to the direct rays of the sun for the other half of the year. This variation causes a warming trend in the Northern Hemisphere, our spring and summer during march to august, and a cooling trend, our fall and winter during September to February. We know these as the seasons. The opposite pattern exists in the Southern Hemisphere.
The surface feature of the land often influences how much energy is absorbed. The term used to describe the amount of light reflected off a surface (hence the amount of energy it absorbs) is Albedo. The higher the albedo of a surface the less light and energy it absorbs (it reflects more light and is brighter or shinier). An example is a snow covered field vs an unplanted, dark soil surface. The snow has a high albedo, it reflects a lot of light, therefore it absorbs very little light, absorbing less energy and heating up slower. The dark field, however, reflects very little light, absorbing most of the light it receives, absorbing more energy and heating up faster. This creates “thermals” over dark fields. Thermals are areas of rising air currents created by warmer, less dense air. Birds, especially predators, are often seen flying/gliding over/in these thermals; the rising air keeps them aloft with very little wing flapping on the part of the bird.
Clouds have high albedo, consequently the surface below the clouds does not receive as much light as an area with fewer clouds.
Climate- the prevailing weather conditions of a place as determined by temperature, precipitation, wind, clouds, and sunlight over a period of years.
Weather- the general conditions of the atmosphere at a particular time and place. Ex. Temperature, precipitation, wind, clouds sunlight. Weather systems are driven by the energy from the sun. Both latitude and surface features on the Earth affect weather and climate.
Thermal energy transfer through the atmosphere: global wind patterns, jet stream, Coriolis effect, weather systems
Currents in the oceans and atmosphere distribute the solar heating from the tropics to the higher latitudes.
Oceans: act as heat sinks. They store large amounts of thermal energy preventing the earth from getting to hot, but also release this energy preventing the earth from getting too cold.
Ocean currents: once heated the surface water can be mixed downward or can be moved across by wind. Surface ocean currents are created by surface wind and their directions are influenced by land masses.
Global wind patterns: are produced by heating at the earth’s surface. The surface heating causes convection (the circulation and distribution of air). Warm air rises (is less dense) and cold air falls (is more dense). Areas of cool air form high pressure systems that push air (wind) to areas of lower pressure or warm air.
Weather systems: large air masses of similar air conditions (weather) are created by heating of the ocean. The air above the ocean warms by conduction and convection creating the air mass. These will move in response to wind patterns and the rotation of the earth.
Coriolis effect: The rotational movement of the air masses and currents on the earth produced by the rotation of the earth. The effect is most evident in large systems and is very difficult to produce in small scale systems. Air masses rotate clockwise in the northern hemisphere and counterclockwise in the southern hemisphere.
Jet stream: currents of extremely fast moving air about 10-15 km above the earth’s surface. They move in a west to east directions because this is the direction the earth spins. Friction between the earth and the atmosphere at ground level pulls the air in the direction of rotation.
Gulf Stream: a 100 km wide “river” of ocean water that starts in the Caribbean and goes to Newfoundland. It follows the east coast of North America
El Nino: a global weather change caused by warm ocean currents moving in different directions than normal. Ex. Warm pacific water moves north along the west coast of North America creating warmer than usual air masses in the western U.S and Canada.

Unique properties of water influence climate

High heat capacity: Large amounts of energy are needed to change the temperature of water compared to other substances. Large bodies of water such as oceans and large lakes have a moderating effect on the air temperature of nearby land communities. Water temperatures change slowly and by small amounts. Large bodies of water absorb a large amount of light and heat during the day and during the summer, but release the heat slowly at night and during the winter.

Phase changes:

Water has high heat of vaporization. This is the energy needed to convert water from a liquid to a gas. The temperature of the water does not change. For water to evaporate a large amount of energy is needed to break the attractive forces among water molecules. The opposite occurs during condensation. For water to form a liquid, it must lose a lot of energy to allow enough molecules to come together and form bonds or attractive forces to pull the molecules closer to each other. Water evaporates when the molecules absorb enough heat to have sufficient kinetic energy to break loose from their neighbouring molecules. This heat can be absorbed from sunlight, from air at the water’s surface, or from other water molecules. When heat is absorbed from other water molecules, they lose energy and cool. This is known as evaporative cooling and it causes bodies of water to remain at a relatively stable temperature. When it rains the clouds release this energy causing a slight warming of the air.

Water has high heat of fusion. This is the energy released to convert water from a liquid state to a solid state (freezing). When water freezes it releases thermal energy, the temperature of the water does not change. When water melts it absorbs thermal energy but the temperature does not change. In spring, the days become linger and the sun begins to warm the land (the sun rises higher off the horizon, more direct sunlight). If large amounts of snow and ice remain from the winter, then much of the suns energy is used to melt them. Therefore, the air temperature does not rise as much as it would in the absence of snow and ice. As winter sets in, the days get shorter and the sun provides less heat than in summer. As liquid water freezes, however, it releases heat. Therefore, the air temperature does not drop as much as it would if there were no water to freeze.

Thermal Energy

Also called internal energy
The total kinetic of all the particles in a substance
The sum of all the vibrations and of the particles

Units for energy are in Joules (J)

Kinetic Energy

Is the energy of motion
Is the translational (shaking/vibration) or rotational motion of the particles

Potential Energy

Is stored energy

Produced or stored in the forces between the molecules that determine the state of matter
It is the forces that hold the molecules together in that state

Temperature

The average kinetic energy of the particles in a substance
Different systems are used to measure temperature. These systems are called temperature scales
There are three different scales: Celsius, Kelvin, Fahrenheit
Kelvin Scale: (K) there are no negative temperatures, zero is the lowest. This is the point at which there is no more motion of the particles; no kinetic energy (0 degrees K). Water freezes at 273 K, boils at 373 K.
Celcius: The lowest temperature is -273 C, water freezes at 0 C and boils at 100 C
K = C + 273

Heat

Is the transfer of thermal (internal) energy
Is measured in Joules (J)
When there is a difference in temperature between two locations thermal energy (heat) will transfer. The faster movement of particles in one area will bump into the slower moving particles in the other area, speeding the slow up and slowing fast particles down.
Heat always travels from a hot area to a cold area until it reaches thermal equilibrium
Thermal equilibrium occurs when there is no net transfer of heat, when the two areas are at the same temperature (all their particles are vibrating with the same speed.

Conduction

The transfer of thermal energy due to the collision of particles (no net movement of substance)
Solids are good conductors b/c particles are more tightly bound allowing for easier collisions.
Metals are the best b/c electrons are more mobile

Convection

The movement of fluid particles from warmer areas to cooler areas
Occurs best in liquids and gases b/c the particles are more free to move among themselves

Radiation