The Atmosphere and Space Chapter 7

What brought the jumper to the ground?

Outline 1. The Atmosphere 1.1 The composition of the atmosphere 1.2 Atmospheric Circulation 1.3 The Greenhouse Effect 1.5 Energy Resources 2. The Effect of the Sun and the Moon on the Earth 2.1 Solar Radiation 2.2 The Earth-Moon System

1. The Atmosphere Atmosphere: the layer of air surrounding the Earth. Air: the mixture of gases that make up the atmosphere

Role of the atmosphere Blocks harmful UV rays Gases for photosynthesis Ensures stable climate by retaining heat Gases for cellular respiration

1.1 The Composition of the Atmosphere 0.04% 78% 21% 0.93% H 2 O (0 to 4%) + particulate matter (smoke, dust, pollen, etc)

Atmospheric Layers

Characteristics of Each Layer Troposphere – 0-15 km As altitude rises, temperature drops (6.5°C per km) Layer where clouds and storms form Stratosphere km as altitude rises, temperature rises due to the ozone layer Fewer air particles as altitude rises OZONE LAYER Mesosphere – 50-80km coldest layer (as altitude rises, temperature drops) Very few air particles

Characteristics of Each Layer Thermosphere km hottest layer because it absorbs most of the sun’s rays Shooting stars (meteors burning) and polar auroras formed Exosphere 500km+ Air particles rare – fairly empty Where satellites orbit

Atmospheric Pressure and Temperature Atmospheric Pressure: the forces of air molecules colliding with each other. Unit of measurement: Kilopascals Symbol: kPa Measured by barometer

Factors affecting Atmospheric Pressure # air particles increases more collisions, more pressure #air particles decreases less collisions, less pressure

Factors affecting Atmospheric Pressure Temperature increase Particles move faster, collide more Stuck in a closed jar this would create a lot of pressure BUT we are not in a jar, particles collide and move away from each other Warm air rises, becomes less dense and therefore LESS pressure Temperature decrease Particles move close together and cool air falls Pressure increases

When preparing to climb mountains such as Mount Everest (8.8 km from sea level), climbers must train hard to increase their cardiovascular fitness. Some also choose to train with high altitude masks. Why?

Altitude & Pressure High altitude = less air = low pressure Low altitude = more air = more pressure

1.2 Atmospheric Circulation Atmospheric circulation: global-scale movement of the layer of air surrounding the Earth. Hot air rises (low density) Cold air falls (high density) Air warmed at the equator rises and moves toward the poles. Cold air from the poles is more dense and moves toward the equator = CONVECTION

Air Movement Wind in the Northern Hemisphere appears to move to the right. Wind in the Southern Hemisphere appears to move to the left. This is a consequence of the Coriolis effect. Video 1 Video 2

Air Masses Air mass: large expanse of the atmosphere with relatively uniform temperature and humidity. Québec is affected by cold air masses from polar regions and warm air masses from the tropics.

When cold and warm meet When two air masses meet: They move horizontally They don’t combine Cold air is denser and sinks under the warm air The border where they meet is called a front. A front is a zone of transition where the direction of the wind, the temperature and relative humidity can change rapidly.

Cold front Cold front: formed when a cold air mass meets a warm air mass. Warm air rises rapidly and then cools  forms puffy clouds = cumulus. Heavy rain and wind!!

Warm front Warm front: formed when a warm air mass rises as it moves toward a cold air mass. Creates light nimbostratus clouds (stratified). Showers slow to disperse

Depressions and Anticyclones Air masses can also move vertically. Anticyclone: Symbol is H (high pressure) cool air particles collide infrequently the particles are closer together the density is high = particles fall to the ground and create an area of high pressure. Depression: Symbol is L (low pressure) Warm air particles collide frequently low density The air mass rises creating a space of low pressure beneath it.

Air masses and Coriolis Effect As the air rises or falls it starts to rotate according to the Coriolis Effect. In the northern hemisphere: anticyclones rotate clockwise and depressions rotate counterclockwise. In the southern hemisphere: anticyclones rotate counterclockwise and depressions rotate clockwise.

Weather + Anticyclones and Depressions In a depression rising air encourages the formation of clouds. (B) In an anticyclone the sky is clear because falling air does not promote the formation of clouds. (A)

Weather + Anticyclones and Depressions H / Anticyclones / high pressure = clear sky, dry, stable L / Depressions / Low pressure = clouds & precipitation

H L Video

Strong depressions + water A cyclone forms when strong depressions form over warm waters of tropical oceans. Cyclone: tropical storm characterized by violent winds revolving around an area of low pressure. The spiral storm can stretch over 1000 kilometers with winds. Cyclone = hurricane = typhoon

1.3 The Greenhouse Effect Greenhouse effect: natural process that allows the Earth to retain some of the heat it receives from the Sun. Video

Atmospheric gases behave like the greenhouse glass  Most of the sun’s rays that reach the Earth’s surface are absorbed by the ground.  The heated ground emits infrared rays (heat):  the rays can exit the atmosphere and are lost in space.  the rays can be trapped by the greenhouse gases which heats the surface furthermore.

Greenhouse gases: Then & Now

Then and Now Then: CO 2 was mainly emitted from forest fires, volcanic activity and cellular respiration. CO 2 was absorbed through photosynthesis and oceans. Natural balance Temperature is relatively stable. Now: CO 2 emissions are increased because of combustion reactions from fossil fuels. Billions of tonnes are released into the atmosphere because of human activity.

Increased CO 2 & decreased O 2 Increased levels of CO2: Burning forests to clear land (combustion) Decreased levels of O2: Deforestation (reduced photosynthesis)

Global Warming More CO 2 emitted in the atmosphere = more heat trapped within the atmosphere. This phenomenon is called global warming and leads to changes in climate. Climate change: the abnormal modification of climatic conditions on Earth, caused by human activity.

Other GHG (greenhouse gases) Methane and nitrous oxide are also emitted in higher concentrations but their effect is not as great as that of carbon dioxide.

If methane = carbon dioxide If methane was emitted in equal concentrations as carbon dioxide it would have an effect 21 times greater on global warming. Methane gas emission sources: Digestions in farm animals Manure storage Household waste decomposition Rice farming

Nitrous Oxide N 2 O Released through: chemical processes Applying nitrogen rich fertilizer to crops

Temperature on the rise From = average temperature rose by 1 o C. If it rises by another degree = more droughts, heat waves and floods + rise in sea levels.

OH wait... That just happened!! “As of Thursday morning, it appears that average temperatures across the Northern Hemisphere have breached the 2 degrees Celsius above “normal” mark for the first time in recorded history, and likely the first time since human civilization began...” March 3, 2016likely the first time February obliterated the all-time global temperature record set just last month. (February 2016)set just last month

1.5 Energy Resources Wind energy: energy that can be drawn from wind. Mechanical to electrical

Video

Wind energy pros and cons Advantages: Wind is a renewable energy No GHG produced Disadvantages: Ruins the beauty of the landscape Can’t predict wind (when or how it blows) Cannot be stored (must combine with other source of energy – usually a dam)

2. The Effect of the Sun and the Moon on the Earth

2.1 Solar Radiation Nuclear reactions of the Sun transform hydrogen into helium which in turn produces energy. Solar energy is radiated across the solar system and reaches Earth in 8 minutes.

Solar radiation Solar radiation contains all the waves in the electromagnetic spectrum.

Only some reach Earth

visible lightOnly visible light, radio waves, some infrared rays and some ultraviolet rays reach Earth’s surface. These rays heat the atmosphere, the oceans and the land. Equatorial regions are hotter because they receive more solar energy due to Earth’s shape and orientation.

Solar energy Solar energy = energy that comes from the sun in the form of radiation through the atmosphere. Technologies that take advantage of solar energy: Passive heating systems: position houses in such a way as to capture as much light and heat possible. Photovoltaic cells: silicon in these “cells” is activated by light and set electrons in motion creating an electric current. (solar panels = large concentration of photovoltaic cells) Solar collectors = large glass panels that capture heat from sunlight and transfer that heat to water in copper pipes just below the panels.

2.2 The Earth-Moon System The moon revolves around the Earth and rotates on its own axis. Rotation and revolution of the moon: 27.3 days.

Tides A gravitational pull of the Moon and the Sun is responsible for daily tides on Earth. Tide: the rise and fall of water in the seas and oceans. It is caused by the gravitational force of the Moon and, to a lesser extent, the Sun. The water bulges in the direction of the Moon.

The opposite side of Earth Why does the opposite side of the Earth also experience simultaneous tides? The water is less attracted to the Moon than the Earth itself is, so the Earth is drawn away from the water, toward the Moon.

Spring and Neap Tides Twice each month, at the time of the new moon and the full moon, the gravitational influences of the moon and sun reinforce one another and cause the tides to rise to greater heights and fall lower than average tides. These are called spring tides At the time of the quarter moon, when the sun, earth, and moon form a right angle, the difference between high and low tide is less than average. These are neap tides.

The Bay of Fun…..dy! The difference in water levels at low and high tide is called the tidal range. The Bay of Fundy (near Nova Scotia) has tides with a range of up to 17 meters.

Tidal Energy Tidal energy: the energy obtained from the ebb and flow of tides. When the tide comes in it fills a water basin. When the tide goes out and creates a difference in water level between the basin and the sea. When a gate is opened, the water in the basin is released to flow through a turbine which generates an electric current.

Tidal energy Advantages Renewable energy source No GHG Reliable because tides are predictable according to the positions of the Sun and the Moon. Disadvantages Costly installation Few places with high tidal range