The Atmosphere The Air Around You Weather- condition of Earth’s atmosphere at a particular time and place Atmosphere-the envelope of gases that surrounds the planet Earth’s atmosphere = N -most abundant gas, ~75% of air we breathe O -2nd most abundant, ~21% Together these two make up 99% of dry air, remain gases = trace gases, most of other 1% is Argon CO2 - less than 1% , but is essential THESE ARE ALL PART OF DRY AIR, BUT AIR IS NOT DRY! H2O vapor – invisible, varies from place to place and from time to time, important role in weather ie. clouds = water vapor condensing, if drops get heavy enough we get rain or snow Particles – dust, smoke, salt, chemicals, pure air only exists in labs The Atmosphere is a system, events in one part affect others Parts = clouds, air, wind, energy

Layers of the Atmosphere Four Main Layers-based on temp. change Troposphere-tropo = turning or changing Weather occurs here Variable conditions ~12 km thick, can be 9 above poles, 16km above equator Most dense, contains most of the mass of the atmosphere As altitude increases temp decreases Stratosphere- strato = layer or spread out Top of tropo to about 50 km above surface of Earth Contains ozone (O3) Ozone protects living things from UV radiation Temperature increases with altitude- due to ozone layer

Layers of the Atmosphere Mesosphere- meso = middle Temp decreases 50-80km above Earth’s surface Upper mesosphere -900C Protects earth from meteoroids meteors collide with the gas particles present in the mesosphere and burn Thermosphere- outermost layer 80 km outward into space, no definite outer limit Temp increases Since sunlight strikes this layer, temp up to 1800oC, BUT doesn’t feel hot because particles are very, very far apart so they do not collide with things to transfer energy. Ionosphere- 80-400 km from surface Exosphere- 400- thousand km’s outward

Layers of the Atmosphere Changing Temperatures The graph shows how temperatures in the atmosphere change with altitude.

The Atmosphere Air has the following properties Air Pressure Air has the following properties Mass Density Pressure – force pushing on and area or surface Air pressure – weight of a column of air pushing on an area Barometer- instrument used to measure air pressure Mercury- contains glass tube, like thermometer, when air pressure increases mercury in tube rises Aneroid-(without liquid) dial connected with spring and levers, chamber shape changes due to pressure, dial moves Units of pressure Atmosphere (atm) Inches of mercury Millibars 1 atm = 1 bar One inch mercury = 33.86 millibars 30 inches of mercury = ? Millibars? Effect of altitude on pressure and density: As altitude Air pressure As altitude Density Effect of Altitude on Pressure and Density How densely packed would the molecules be at the different altitudes?

Energy is Earth’s Atmosphere The Atmosphere Energy is Earth’s Atmosphere Electromagnetic (EM) waves-energy that can travel through a vacuum (space) Classified according to wavelength Most energy from sun comes in form of Visible light-ROGBIV Red /Orange longest wavelength Blue/Violet shortest wavelength Infrared radiation- not visible, longer wavelength than red light Ultraviolet radiation- not visible, shorter wavelength than violet, causes sunburns Energy in the Atmosphere Some wavelengths reach Earth’s surface. Other wavelengths are completely or partially absorbed in the atmosphere. Radiation From the Sun Energy travels to Earth as electromagnetic waves. What are the types of electromagnetic radiation in the diagram?

Energy in Earth’s Atmosphere The Atmosphere Energy in Earth’s Atmosphere Scattering- reflection of light in all directions Gas molecules in atmosphere scatter short wavelengths of visible light more than long wavelengths This is why the sky is blue Energy at Earth’s Surface Complete each sentence with a word from the Word Bank to learn what is happening to the energy at Earth's surface and in the lower atmosphere.

Energy in Earth’s Atmosphere The Atmosphere Energy in Earth’s Atmosphere The Greenhouse effect- natural process that keeps Earth’s temperature stable and comfortable for most living things There is evidence that human activities are altering this process Greenhouse Effect The greenhouse effect is a natural heat-trapping process. What is the sequence of events that causes it to occur?

The Atmosphere Heat Transfer Temperature- average kinetic energy of particles in a substance Measured with a thermometer Thermal energy –total kinetic energy of all particles in a substance Tea in pot vs. tea in a cup… Which has higher temp? Which has higher thermal energy? Temp Scale Celsius- 0 = freezing, 100 = boiling Fahrenheit- 32 = freezing, 212 = boiling Convert Fahrenheit to Celsius C= (F-32) x 5/9 Celsius to Fahrenheit F= C x 9/5 +32 Heat- thermal energy transferred from hot to cold Conduction Convection Radiation These three processes work together to heat troposphere

The Atmosphere Winds Unequal heating of atmosphere differences in pressure wind Wind- movement of air parallel to Earth’s surface Described by Direction – measure by wind vane, name tells you what direction wind came from (south wind blows from South to North) Speed-anemometer Windchill factor- increased cooling that wind can cause Local Winds Sea Breeze-occurs during the day, land warms up faster than water, warm, less dense air rises creating low pressure area, cool air blows inland from the water Land Breeze-occurs during the night, water stay warm longer than land, air above it is less dense so it rises, cool air from the land blows out toward water

The Atmosphere Global Winds Winds that blow steadily from specific directions over long distances, also caused by diff. in pressure See diagram on p. 446 for example of unequal heating How do global winds develop? Temp. differences between poles and equator produce giant convection currents= Global convection currents Air pressure lower near the equator and greater near the poles Winds at Earth’s surface blow from poles toward equator Higher in the atmosphere, air flows away from equator toward poles – this produces global winds

The Atmosphere The Coriolis Effect The curving of the global winds due to the rotation of the Earth If the Earth did not rotate the winds would blow straight Wind in northern hemisphere turn right Wind in southern hemisphere curve left Global wind belts Doldrums- equator, calm area where warm air rises Horse latitudes-30oN and S, calm area of sinking air Trade winds-30oN and S to equator , toward equator Prevailing westerlies-30-60oN and S latitude, away from equator Polar Easterlies- 0-30o N and S latitude, away from poles

The Atmosphere