Which photo is about weather? Which is about climate?

WEATHER: conditions of temperature, air pressure, cloud cover, precipitation, humidity, etc that occur at a particular place at a particular time.

Southern Alberta – Summer of 2005

• Weather and climate result from interactions between the different parts of our biosphere.

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BIOSPHERE: the parts of earth that have the conditions suitable for supporting life. It is made up of three parts.

ATMOSPHERE: air

HYDROSPHERE: water

LITHOSPHERE: earth

ENERGY FROM THE SUN

Three Structural Zones

• The Biosphere is broken into three basic structural zones
• Lithosphere
• Earth’s crust
• The outer solid part of the Earth
• Hydrosphere
• The water portion of the Earth’s crust
• Atmosphere
• The gasses that surround the Earth.

The Atmosphere

• A mixture of gases extending about 500 km from the surface of Earth
• Nitrogen (78%)
• Oxygen (21%)
• Water vapour (part of the hydrosphere)
• Dust particles

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Stratosphere (10 to 50 km)

• Temp increases as you go up in this layer

Troposphere (0 to 10 km)

• Average temp (15 ̊ C)
• Nearly all life contained in this layer
• Contains ozone (O₃) gas

Mesosphere

• Temp decreases

Thermosphere

• Gets really hot
• Auroras (caused by earth’s magnetic field)

Layers of the Atmosphere:

Auroras are caused by charged ejected by the sun. Thankfully, these particles are deflected by the Earth’s magnetic field.

These particles accumulate at the poles where they excite air molecules to produce beautiful streams of plasma called “auroras”.

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Altitude and Temperature

• In the troposphere, temperature decreases with altitude.
• This is one reason for the upper limit of plant growth on mountains and the formation of glaciers at high altitudes.

Tim & Moby

Earth’s Atmosphere

The Lithosphere

• The solid part of the earth – floats on the semi-molten mantle layer
• Life is found to depths of several kilometers

The Hydrosphere

• All of the earth’s water that supports life
• 97% marine saltwater
• 3% freshwater (most of which is frozen as mountain glaciers and continental ice sheets)

Organisms are Adapted to Deal with Climate

• Describe the climate that goes with each adaptation:

Dry: fat leaves prevent water lose

Wet: air filled bladders for floatation

Cold: Tiny ears prevent heat loss

Hot: large, thin ears maximize heat loss

Energy Flow in the Biosphere

RADIATION is the process by which solar energy reaches the earth

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• Defined as the mechanism of energy transfer in which atoms or molecules emit electromagnetic waves.
• They release this energy only when they interact with matter
• Solar radiation consists of many different wavelengths affected differently as they enter the atmosphere

• Solar Energy entering the atmosphere
• 49% is absorbed by oceans and land
• 42% is absorbed, reflected and scattered by the atmosphere
• 9% is reflected by the Earth’s surface

Incoming and Outgoing Radiation

Do Now

• What causes different seasons?

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• Does adding salt to water change how fast/hot it boils? Why?

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Albedo

• Albedo is a measure of how much light is reflected by a surface.

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• Light from the sun is either absorbed and converted to heat, or reflected back to space.
• Snow, ice, clouds and suspended particles (e.g. volcanic ash) have high albedos

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• When light is reflected back to space, it can have a global cooling effect.

The Natural Greenhouse Effect

• Greenhouse gases (GHGs) in our atmosphere trap in heat radiated from earth.
• GHGs include water vapour, carbon dioxide and methane.

• Without the greenhouse effect, earth would be covered completely with ice.

Visible light and U.V.

Infrared

Energy Flow in the Biosphere

• A region’s climate is largely determined by the amount of solar radiation striking that part of earth’s surface (Insolation)
• Insolation is determined by the angle at which the light strikes.
• This is why it’s hotter at the equator than at the poles.

More energy per m²

Q: What causes the different seasons?

• Some people think that Earth is closer to the Sun in the summer and that is what causes the hot weather, but this is not true.
• Earth is actually further from the Sun in the summer and closer in the winter.
• However, these minimal changes do not effect our seasons.
• Earth orbits around the sun in an ellipse, not a circle.
• Since Earth is tilted, different concentrations of sunlight reach the surface.
• This change of concentration of sunlight rays is what creates our different seasons.

• What causes the seasons?

• It’s summer in the Northern Hemisphere when the north pole is tilted toward the sun

• It’s winter in the Northern Hemisphere when the north pole is tilted away from the sun

Heat and the Hydrosphere

• Earth’s relatively moderate climate is largely thanks to the presence of so much water.
• Water has the ability to store tremendous amounts of heat.

(i.e. water has a high specific heat capacity – the amount of energy needed to raise the temperature of a 1 gram of a substance by 1 degree Celsius.

• Water’s specific heat capacity is

• Water heated in the tropics flows north and dumps its heat. This reduces temperature extremes.

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Water’s Unique Properties

• Water has a lot of cohesion (water molecules are attracted to each other)
• This is because water is a polar molecule (meaning that one end is more positive and the other end is more negative.)
• Water can be bent by electric attraction

H-Bond Movie (PG-Rated)

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• The cohesion comes from hydrogen bonds because of the attraction between the positive hydrogen atoms and the negative oxygen atoms.

• Water has surface tension: and attractive force between water molecules on the surface.

• Because of water’s H-bonds, it has a high melting point (0 degrees C) and a high boiling point (100 degrees C)
• Ice is less dense than water, so it floats (the only substance that does this)

Calculating Heat Transfers

• The amount of energy gained by a substance as it increases in temperature:

Energy gained in Joules (J)

Mass in grams (g)

Specific heat capacity

Change in temperature in degrees C

NOTE THAT MASS IS IN GRAMS!!!!

How much energy is released when 55 g of water cools from 35ºC to 12ºC?

Q= -5.3 x 10³ J

-Q = EXOTHERMIC! Less E_k

What mass of sea water could have its temperature lowered from 25 ºC to -10 ºC if it released 120 kJ of energy?

• Released Energy is an Exothermic Reaction

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Challenge

• A 1000 g block of ice, at −25.0ºC, is warmed by 35 kJ of energy. What is the final temperature of the ice?

Energy Transfer in the Hydrologic Cycle

• Earth’s hydrosphere undergoes a constant cycle involving transport and transformation called the hydrologic cycle
• The sun provides the energy that drives the process of the hydrologic cycle.

• The hydrologic cycle involves changes in phase that either absorb energy (endothermic) or release energy (exothermic).

fusion

H₂O _(s)

_(ice)

H₂O _(l)

_(water)

H₂O _(g)

_(vapour)

fusion

Condensation

Vaporization

Heat of Fusion +6.01 KJ/mol

Heat of freezing -6.01 KJ/mol

Heat of Vaporization +40.65 KJ/mol

Heat of Condensation -40.65 KJ/mol

Is steam liquid or gas?

Changing Phases

Released = negative

Absorbed = positive

Water’s Heating Curve

• While water is changing states it’s temperature does not change
• e.g. when water is melting all of the surrounding heat is used to change ice to liquid, not to heat it up.

How do you keep the plants in your greenhouse from freezing

Water Vapour

Water

vapour

• Heat of fusion: the heat of fusion (H_fus) of a substance is the amount of energy required (or released) to melt (or freeze) one mole of a substance.
• Heat of vaporization: the heat of vaporization (H_vap) of a substance is the amount of energy required (or released) to convert one mole of a substance from liquid to gas (or vice versa)

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Terms

Amount of the substance in moles (mol)

Heat of vaporization (KJ/mol)

Heat of fusion (KJ/mol)

Amount of heat energy absorbed or released (kJ)

Calculating Heats of Fusion and Vaporization

Let’s look the example problems on p.383

Then do practice problems 10-14

How much energy is released when 2.05 mol of water vapor, at 100°C, condenses with no change in temperature?

Q = -83.3 kJ

How much energy is absorbed when 4.50 mol of liquid nitrogen vaporizations with no change in temperature?

Q = 25.1 kJ

If 175 kJ of heat caused a chunk of ice at 0ºC to melt to liquid water at 0ºC, how many moles were in the ice? �

n = 29.1 mol

• Precipitation
• atmospheric water falling in the form of
• rain, snow, sleet, hail, dew...
• Groundwater
• water on the surface or just below the surface
• lakes, rivers, oceans, aquifers, artesian wells…
• Evaporation
• water that has been heated by the sun rises as water vapor.

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Water cycle Terms

• Condensation –
• Water vapor that forms into water droplets when cooled
• Cellular Respiration
• the process in which living organisms convert the energy of sugars into energy used by body processes
• Transpiration
• the loss of water through the leaves of plants

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Water cycle Terms

Human Impact on Global Climate

Human activities are adding to the GHG’s in the atmosphere – causing a general warming of the global climate

GHG’s include:

• Carbon dioxide (CO₂)
• Methane (CH₄)
• Nitrous Oxide (N₂O)
• Water Vapour (H₂O)_(l)

• The enhanced greenhouse effect

Human Sources of GHG’s

CO₂

Fossil Fuel Combustion

• automobiles
• electricity generation
• Industry

CH₄

N₂O

Decay without oxygen present

• livestock

• automobiles
• fertilizer

Human Sources of GHG’s

CO₂

CH₄

N₂O

Which of the following human produced GHGs are NOT produced by automobiles?

A.

B.

C.

Tracking Atmospheric CO₂

• Due to human activities, carbon dioxide and other GHG’s are rising exponentially.

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• Historical data is collected by analyzing tiny bubbles in yearly layers of ice.

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• Average yearly temperature can also be measured this way.

Evidence of Increasing Global Temperature

Evidence of Increasing Global Temperature

• Average global temperature increased by about one degree C over the last century.

Trying to predict how a complex system will behave in the future depends on:

• past patterns
• knowledge of the present state of the system
• understanding how the system works

Predicting the Future will Always be Uncertain

Scientists use computer models to try to predict how earth’s climate will behave in the future.

Potential Effects of Climate Change

International Efforts

THE MONTREAL PROTOCOL

• phase out CFC’s (a GHG)
• first major international agreement addressing earth’s atmospheric health

U. N. FRAMEWORK CONVENTION ON CLIMATE CHANGE

• laid ground work for an international action plan to address climate change
• focused on sustainable development (using resources without endangering future generations)

KYOTO PROTOCOL ON CLIMATE CHANGE

• U. N. treaty
• Canada agreed to reduce GHG emissions to 6% below 1990 levels.
• 2006: Canada said it will no longer try to meet it’s Kyoto goals

Emission-reduction credits (if you take GHG’s out of the atmosphere) – can be bought and sold internationally

Personal Choices