CHAPTER 4 ATMOSPHERE

Atmosphere Definition: a thin layer of air that forms a protective covering around the planet WITHOUT THE ATMOSPHERE: days would be extremely hot nights would be extremely cold Maintains a balance between: Heat absorbed from the Sun Heat that escapes back into space Also protects us from Sun’s harmful rays!

Earth’s Atmosphere Mixture of Gases Solidsall surround the planet Liquids Earth’s atmosphere TODAY is much different than it was billions of years ago!

2 billion years ago…….. Earth’s early atmosphere: produced by erupting volcanoes Contained Nitrogen and Carbon Dioxide…. LITTLE OXYGEN Early organisms: released oxygen Made food with aid of sunlight Limited to ocean: Deep enough in ocean to be protected from rays but close enough to get sunlight

NEXT……. A layer rich in ozone (O3) formed in the upper atmosphere This layer protects the Earth from the Sun’s harmful rays This layer allowed: green plant to flourish release in even more oxygen

Gases in the Atmosphere Today’s atmosphere is a mixture of the following gases: Nitrogen: 78% Oxygen: 21% Argon: 0.93% Carbon Dioxide: 0.03% Neon, Helium, Methane, Krypton, Xenon, Hydrogen, Ozone: Trace

Solids and Liquids in the Earth’s Atmosphere In addition to gases, the atmosphere contains small, solid particles: DUST: wind picks them up off the ground and carries them SALT: picked up from ocean spray POLLEN: given off from plants

continued The atmosphere also contains small liquid droplets other than water droplets in the clouds Example: volcanic eruption may contain liquid droplets and solids These then travel thousands of miles.

Layers of the Atmosphere 5 layers EXOSPHERE THERMOSPHERE MESOSPHERE STRATOSPHERE TROPOSPHERE EARTH

TROPOSPHERE Where we study, eat, and play Lowest of all the layers 99% of water vapor 75% of atmospheric gases Rain, snow, clouds 10k high

Stratosphere Layer above the troposphere Starts at 10km and extends to about 50km Contains “ozone”: protects earth from sun’s rays

Mesosphere From 50km to 85km Where shooting stars are located

Thermosphere Named for its high temperatures Thickest layer Begins at 85km and extends to 500km above the Earth’s surface

STOP!!! Ionosphere This is located WITHIN the mesosphere and thermosphere It is a layer of electrically charged particles Allows radio waves to travel across the country

Exosphere Where the space shuttle orbits the Earth There are so few molecules in this layer, the wings are useless. Instead, the rocket relies on bursts from its thrusters. Beyond exosphere: outer space

Atmospheric Pressure Like a football player in a tackle Atmospheric gases have mass Atmospheric gases extend hundreds of kilometers above the Earth’s surface Earth’s gravity pulls the gases toward its surface Result: molecules closest to the Earth’s surface are closer together Harder to breathe in the high mountains. Jets must remain pressurized (cabins) so that people can breathe.

Atomospheric Pressure Diagram v

Temperature in Atmospheric Layers Main source of energy on the earth: SUN The rays must pass through the atmospheric layers. Some layers contain gases that absorb the sun’s energy. Some layers DO NOT contain these gases. THEREFORE: various layers have different temperatures Page 95

How sun’s rays are absorbed: Troposphere: warmed from earth’s surface Top of a mountain is cooler than bottom For every km you climb : temp 6.5 Stratosphere: molecules of ozone absorb sun Temperature rises with increasing altitude Mesosphere: temps decrease with altitude Thermosphere: temps increase with altitude FEW molecules are in these layers

The Ozone Layer Between 19km to 48km high Made up of oxygen YOUR LIFE DEPENDS UPON IT! Ozone absorbs most of the ultraviolet radiation that enters the atmosphere Too much exposure: CANCER

How to look for skin cancer

CFC’s : chlorofluorocarbons Air pollutants causing the ozone to break down Found in: Aerosol sprays Air conditioners, Refridgerators Foam packaging Pg 96: breakdown RESULT: more ultraviolet radiation reaches the earth

Section 2: Energy Transfer in the Atmosphere Sun: provides energy This energy drives: Wind Ocean currents Allows plants to grow

Sun’s Energy 3 things can happen to the sun’s energy when it reaches the Earth: 1. Some is reflected back into space 2. Some is absorbed by the atmosphere 3. Some is absorbed by the land and water on Earth’s surface

Sun’s rays: HEAT Heat: energy that flows from an object with a higher temperature to an object with a lower temperature. Heat from the sun’s rays are TRANSFERRED through the atmosphere: 1. radiation 2. conduction 3. convection

Radiation Sitting on the beach & feeling the sun’s rays You feel the heat on your body! Radiation: energy that is transferred in the form of rays or waves

Conduction If you WALK on the hot beach, your feet heat because of CONDUCTION. CONDUCTION: the transfer of energy that occurs when molecules bump into one another. Balloon Experiment Molecules are always in motion Warmer molecules move faster than colder molecules Warmer transfers energy to colder

Balloon Experiment: Conduction

Convection Convection: the transfer of heat by the flow of material When air is warmed, particles move apart. When air is cooled, particles slow down

The Water Cycle Hydrosphere: all waters of the earth. Evaporation: water changes from liquid to gas Condensation: water vapor changing to a liquid Clouds form water vapor DRAW and EXPLAIN CYCLE!