Global Systems Notes 2017.doc

Science 10 Global Systems Notes A. The Biosphere

 means the “living globe”,

 is a thin layer around the Earth that supports life  the biosphere is composed of 3 layers that interact:

1. Atmosphere

 thin layer of protective gases surrounding the Earth

 acts like a fluid and exerts a constant pressure on our body

 approximately 500 km thick

 it is mainly made up of:

 78% nitrogen (needed for plant growth)

 21% oxygen (needed by organisms, maintained by photosynthesis)

 contains some atmospheric dust (ex. soot, pollen) The Ozone Layer

 ozone is O3(g)

 it absorbs UV radiation from the sun

 the ozone “holes” are regions in the ozone layer that have thinned

 “holes” have been identified over both poles  reasons for depletion:

1. chemical reaction of O3(g) with chlorofluorocarbons

(CFC’s )

2. natural cycles in the atmosphere

2. Lithosphere

 all land on Earth from surface to 100 km below

 runs under thecontinents and oceans

 warmed by the sun and by the molten material in the Earth’s mantle

 altitude affects temperature (higher altitude = lower

temperature)

 mountains cause warm air to rise which releases moisture

3. Hydrosphere  all water on Earth

 covers approximately 70% of the Earth’s surface

 97% is salt water in the oceans

 3% is fresh water, mainly locked in glaciers but also as lakes, streams, etc.

 includes water vapour in atmosphere

 water is constantly cycled throughout the biosphere and the amount of water on Earth remains the same

B. Flow of Energy in the Biosphere

 biosphere is maintained by a constantflow of energy from the sun  regions near the equator receive more thermal energy

 insolation is the amount of solar energy received by a region

o depends on:

1. angle of incidence

 angle at which the sun’s rays hit the surface of the earth

 depends on latitude – equator receives the most, angle is 0

2. angle of inclination

 the tilt of the earth’s axis…23.5

 sun’s rays to strike the equator directly

 less direct at higher latitudes (as you move to poles)

 causes uneven heating of the earth, resulting in weather patterns

 causes there to be seasons

 summer occurs when the pole is

tilted towards the sun

 winter occurs when the pole is tilted away from the sun  solstice is the shortest (winter - Dec 21) and longest

(summer - June 21) days of the year

 equinox is when the hours of daylight and darkness are the

same because the centre of the sun is over the equator

 March 21 – vernal equinox (spring)

 September 21 – autumnal equinox (fall)

 solar energy can be reflected, absorbed or trapped

Solar Energy Reflection

 albedo is the degree to which materials reflect solar radiation

 the lighter the colour, the higher the albedo

 high albedo = snow, ice, water, clouds  low albedo = soil, dark rocks, forests

Solar Energy Absorption

 absorbed by non-living components and eventually re-radiated back into space as heat

 absorbed and stored by chlorophyll-containing organisms by way of photosynthesis

 drives the water cycle which cycles water through the biosphere and maintains life on earth

 occurs as a result of energy being absorbed and released by H2O molecules… causing phases changes (eg. liquid to gas)

Trapping of Solar Energy

 caused by greenhouse gases in the troposphere trapping heat that is reflected from the earth

 High energy UV light enters the atmosphere, is reflected from the earth and is converted to lower energy IR (infrared) radiation. This radiation is trapped by greenhouse gases and warms the earth so that life can exist.

 greenhouse gases:

o methane

o carbon dioxide o nitrous oxide o water vapour

 greenhouse effect is natural but is also being enhanced by human activities (global climate change, rising global

temperatures)

C. Thermal Energy Transfer

 energy is transferred locally and also

globally

 causes temperature increase

 there are three types of transfer:

1. Radiation

 transfer of heat by wavesof radiant energy from the sun

2. Conduction

 transfer by direct contact, usually in

solids

 faster moving particles transfer energy to

slower moving particles

3. Convection

 transfer by movement of particles from one

place to another, usually in liquids and gases (fluids)

 less dense particles rise, more dense sink

 movement creates a convection current

 occurs in both the troposphere and hydrosphere  moves warm air towards the poles (transporting heat)

 air at equators is warmer than air at the poles

 this creates huge convection currents as the warm air rises

above the equator then cools and sinks towards the poles

 creates Hadley cells in the atmosphere

 it causes wind

D. The Coriolis Effect

 caused by the rotation of the Earth

 Earth spins towards the east

 this spinning causes a deflection in the

motion of winds called the Coriolis effect

 air moving from the equator to the poles is

deflected to the east

 air moving from the poles to the equator is

deflected to the west

E. Global Winds

 can be regional ie) horizontal movement of air

 can be global ie) movement of air masses around globe

 global wind patterns are created by: 1. convection currents

2. Coriolis effect

 at the equator, warm air rises and the Coriolis effect deflects the air… called the tradewinds

 The westerlies:  The easterlies:

 the jet streams are bands of fast moving air in the stratosphere that affect weather systems

F. Energy Transfer in the Hydrosphere

 water in the oceans is moved by the global winds

 the tradewinds and westerlies move warm water between the equator and the poles

 land masses (continents) cause currents to change direction

G. Biomes

 a biome is a large geographical area with a particular range of

temperature and precipitation levels

 biomes are open systems that exchange both matter and energy with their surroundings

 the Earth has several different biomes:

o tundra

o taiga (boreal forest) o deciduous forest o grasslands

o desert o rainforest  Canada has four biomes:

o tundra o taiga o grasslands

o deciduous forest

H. Climatographs: Analyzing Energy Flow

I. Climate Change

 climatologists believe that we are experiencing climate change and that

human activity plays a role in this change

 the four main greenhouse gases generated by human activity are:

 carbon dioxide  methane

 dinitrogen monoxide  water vapour

 the most common greenhouse gas is carbon dioxide and was given a Global Warming Potential (GWP) rating of 1

 based on the graph, the CO2

concentration in the time period 1700 to 2000 rises exponentially  during the Industrial Revolution

in the 1900’s, human activity became more dependent on fuel consumption that contain large amounts of carbon

 scientists collect data about the concentration of greenhouse gases over time by analyzing:

 a carbon source is any process that releases CO2(g) into the atmosphere

eg) combustion, respiration

 a carbon sink is any process that removes CO2(g) from the atmosphere

eg) photosynthesis, dissolving in oceans

 the enhanced greenhouse effect is the change in Earth’s net radiation budget caused by the increase in human-generated greenhouse gases  global warming is one piece of evidence that the Earth is experiencing

climate change

 other observed signs of climate change are:

1. rising sea levels 2. retreat of glaciers

3. frequency of severe storms

4. earlier flowering of flowering plants

5. decline of fish stocks as ocean temperatures rise

 scientists agree that the Earth’s temperature has increased, but some attribute this increase to a natural climate cycle and not as a direct result of human activities

J. Water

 water is a polar molecule which means it has a positively charged end and a negatively charged end

 it behaves like magnets with the positive end of one molecule attracting the negative end of another molecule

 attraction between water molecules is called hydrogen bonding and it gives water some unique properties:

 high surface tension is caused by high cohesive and adhesive forces

of attraction

 organisms can use this to their advantage eg) water strider

2. More Than One State

 water is one of the only substances that can exist in all three states (phases) at the same time

 each change of state involves an exchange of energy with the surroundings

3. High Melting and Boiling Points

 allows for a wide range of temperatures on earth

4. Density

 water is unique in that it is less dense as a solid (ice floats!)

 it is most dense at 4C

 this is good, especially for aquatic life…lakes freeze at the top and the most dense water (4C) sinks to the bottom

5. High Specific Heat Capacity

 specific heat capacity is the amount of heat energy required to change the temperature of a specific mass of a substance by 1C

 water has a very large specific heat capacity, which means that it takes absorbs a lot of energy and releases it slowly

 also moderates global climate

 cities at the same latitudes have different climates depending on how close they are to a large body of water and warm vs. cold ocean currents eg) Vancouver, Labrador, Lethbridge

 we can calculate heat energy using the following formula:

Q = mcΔt

where: Q = heat energy in Joules (J)

m = mass of substance in grams (g) c = specific heat capacity in J/gC Δt = change in temperature in C

Example 1

Example 2

Calculate the heat required to raise the temperature of 400 g of copper from 10.0°C to 50.0°C.

Example 3

Calculate the heat required to raise the temperature of 30.0 g of gold from 10.0°C to 50.0°C.

Example 4

Calculate the heat required to raise the temperature of 60.0 g of air from 10.0°C to 70.0°C.

6. Unique Heat of Fusion

 the amount of heat energy required to convert one gram of a solid into its liquid state with no change of temperature

Hfus = Q or Q = nHfus

n

where: Hfus = heat of fusion in J/mol or kJ/mol

Q = heat energy in J or kJ n = number of moles in mol

Example 1

Calculate the heat of fusion of a substance if 2000 J of heat energy is applied to 0.694 mol.

Example 2

Calculate the heat of fusion of a substance if 1.05 kJ of heat energy is applied to 0.231 mol.

Example 3

Calculate the heat energy absorbed in order to melt 12.0 g of ice. Hfus = 6.01 kJ/mol

Example 4

Calculate the heat of fusion of a substance if 2050 J of heat energy is applied to 0.138 mol.

Example 5

Calculate the heat of fusion of a substance if 3.07 kJ of heat energy is applied to 0.253 mol.

Example 6

7. Unique Heat of Vaporization

 heat of vaporization is the amount of heat energy required to convert

one gram of a liquid into its vapour form with no change of temperature

Hvap = Q or Q = nHvap

n

where: Hvap = heat of vaporization in J/mol or kJ/mol

Q = heat energy in J or kJ n = number of moles in mol

Example 1

Calculate the heat of vaporization of a substance if 5000 J of heat energy is applied to 0.325 mol.

Example 2

Calculate the heat of vaporization of a substance if 4.00 kJ of heat energy is applied to 0.226 mol.

Example 3

Calculate the heat energy absorbed in order to vaporize 12.0 g of water. Hvap = 40.65 kJ/mol

Example 4

Calculate the heat of vaporization of a substance if 3024 J of heat energy is applied to 0.135 mol.

Example 5

Calculate the heat of vaporization of a substance if 4.07 kJ of heat energy is applied to 1.22 mol.

Example 6