Composition 78% Nitrogen remain 21% Oxygen constant 1% Trace gases, Carbon Dioxide, Water Vapor, dust **concentration water vapor in the atmosphere varies with the seasons, **solids such as dust, ice and salt (picked up by wind) help the clouds form
Layers of the Atmosphere Troposphere -- 0-10 km (closest to Earth) Tropo – means “Changing” We breath this part, planes fly here Contains the most water vapor Weather occurs, Most pollution is found MOST DENSE The THINEST At the top ~temp. lower to -60 C
Stratosphere -- 10-50 km Strato- means “spread out” Made of conc. ozone which absorbs UV radiation Ozone layer at about 25 km Gets heated ( up to 0 C from -60) Ozone absorbs harmful rays from Sun, and converts to Heat Mesosphere -- 50-80 km Meso- means “middle layer” Temperature decreases (-40 to -80 C at top) Protects Earth from meteoroids.
Ozone (O 3 ) Ground-level ozone is an air pollutant *harmful effects on the respiratory systems of animals Ozone in the upper atmosphere filters potentially damaging ultraviolet light from reaching the Earth's surface.
Thermosphere -- 100-400 km Thermo- means heat Very thin layer, solar radiation absorbed Contains “Ionosphere” Temperature increases (-80 to 1800 C at the top) Aurora Borealis (Northern Lights) located here. Exosphere – 400+ km (outermost layer) Exo- means “Outer” Helium and Hydrogen No clear outer boundary Satellites found here http://vimeo.com/16917950
Visible Light and some Infrared get through But that’s NOT all!!! images are courtesy of Windows to the Universe, http://www.windows.ucar.edu
Why is the sky blue? Transmitted light (from sun, light bulbs, fire etc…) is made of a spectrum of colors – looks white --Light moves through air --it scatters in all directions --Longest wavelengths of light = red/orange Shortest wavelengths = blue/violets Shortest wavelengths = blue/violets (shorter wavelengths scatter the most light) --Since blue rays scatter the most, they reach our eyes from all directions and we see more blue than any other color
Atmospheric gases scatter blue light more than other wavelengths, giving the Earth a blue halo when seen from space.
What Makes a Red Sunset? light has more atmosphere to pass through to get to our eyes, only the strong red light can make it.
Properties of the Atmosphere 1. Temperature -- measures how fast molecules are moving (particles in any material = random motion) --higher the temp of material/faster particles are moving Temperature inversion: When warm air is on top of cooler air -lack of thermal energy -smoke, fog, pollution
Conduction heat transfer through matter. Atoms or molecules must touch each other. Type of heat transfer in solids. Metals conduct heat well. Air is not a good conductor of heat.
For example, a spoon in a cup of hot soup becomes warmer because the heat from the soup is conducted along the spoon.
Convection heat transfer by the movement of mass from one place to another. Can take place only in liquids and gases. Convection occurs when areas of cool dense molecules and warmer less dense molecules move near each other.
The heat moves with the fluid in a circular pattern because when areas of cool dense molecules are warmed, they become less dense and rise. When areas of warm less dense molecules move into cooler areas of molecules, they becomes more dense and falls. Examples: movement of plate, ocean currents, home furnace heating & circulating air
Radiation Radiation is electromagnetic waves that directly transport ENERGY through space. Sunlight is a form of radiation. Radiation is the only way heat is transferred (can move) through the relative emptiness of space. Radiation does not heat air directly as it travels through the atmosphere from the sun. Air is heated by reradiated waves of molecules on the surface of the earth that absorb energy from the sun.
2. Air pressure Air has a mass that is constantly pushing down on us -due to gravity pushing down on us -due to gravity Pressure is the greatest on the Earths surface and will decrease as the mass of air above you decreases ** Relationship between Air pressure and Temperature Temperature Air Pressure Density of Air IncreasesIncreasesDecreases DecreasesDecreasesincreases
3. Humidity --the amount of water vapor in the air, -- 2 ways to express water vapor content in atmosphere: a) dew point: the temp. in which condensation occurs b) relative humidity: the amount of water the air at a given temp. can hold, expressed in % Ex. relative humidity is 50% - air contains 50% of the water vapor needed for air to be saturated
Wind – moving air --created by an imbalance between warm (less dense) & cool (more dense) air-creates high/low pressure areas --wind speed increases with height in atmosphere
Clouds Why clouds are white? Water droplets in clouds have many surfaces to reflect light, and scatter almost all the light and look white even though clouds are nearly transparent Ex. Root-beer foam, salt/sugar crystal foam - white / liquid –colored *walls of the foam bubbles are so thin – reflect light while light is absorbed by the liquid
Cloud Formation: 1.Warm, humid air rises 2.Air cools, due to convection currents 3.Dew point is reached 4.Water droplets form around a small particle of dust/salt 5.The salt, dust, or ice at the center of the droplet is called: condensation nucleus 6.If the air mass rises very rapidly, rain occurs **This can take place at many different altitudes, which makes different types of clouds **If it takes place at ground level = fog
Types of Clouds Name of cloud Height of cloud Cirro- Above 6000m Alto-2000-6000m Strato- Below 2000m 3 Main groups Luke Howard – 1803 “Man that named the clouds”
Each group is then described by shape: Descriptive name Shape Cirrus Curls of hair Wispy stringy clouds Cumulus Heap Puffy, lumpy Stratus Layer Sheets of clouds Nimbus Rain Low gray rain clouds
Describe these clouds: Height and shape are combined to form name of clouds: 1.puffy clouds at 2000-6000m: 2.low gray clouds below 2000m: 3.above 6000m, wispy clouds: 1. Altocumulus 1. Altocumulus 2. Nimbostratus 3. Cirrus
Vertical Developing Clouds Air of cumulus cloud = unstable Cloud warmer than surrounding air It will continue to grow upward Large, puffy rain clouds = Cumulonimbus Can reach past the troposphere Result in super-cell thunderstorms, severe weather Draw:
Precipitation --All forms of weather that fall from clouds to ground Four Main types: Rain,Snow,Sleet, & Hail Formation of precipitation: Coalescence – warm cloud droplets collide and form larger droplets which are too heavy to stay aloft = resulting in Rain
Types of Precipitation Remember the water cycle song :o) Remember the water cycle song :o) Snow = in cold clouds ice crystals are formed Sleet = convective currents carry droplets up/down through freezing & nonfreezing air, forming ice pellets Hail = if up/down motion is extremely strong & takes place over long stretches of atmosphere, forms very large ice pellets
The End http://www.williamsclass.com/EighthScience Work/Atmosphere/EarthsAtmosphere.htm http://www.williamsclass.com/EighthScience Work/Atmosphere/EarthsAtmosphere.htm http://www.williamsclass.com/EighthScience Work/Atmosphere/EarthsAtmosphere.htm http://starryskies.com/solar_system/Earth/at mosphere.html http://starryskies.com/solar_system/Earth/at mosphere.html http://starryskies.com/solar_system/Earth/at mosphere.html