Chapter 17 page 474

The Atmosphere: Structure and Temperature

A. Atmosphere Characteristics1. Introductiona. Earth has a unique atmosphere for lifeb. Weather1)Specific time and place2)Short term and constantly changing

c.Climate1)Long term2)Based off observations of weather3)Helps describe a place or region

2. Composition of the Atmospherea. Major components

1) Nitrogen – 78%2) Oxygen – 21%3) Argon – 0.93%4) Carbon dioxide

a) 0.039%b) Helps warm the earthc) Needed for plant growth

3. Variable Componentsa. Water vapor

1) Source for clouds and precip2) Absorbs heat from earth3) Absorbs some solar radiation

b. “Dust”1) Sea salts from breaking waves2) Fine soil3) Smoke and soot4) Pollen and microorganisms5) Ash

c. Ozone1) O3

2) Formationa) O2 absorbs UV light

b) O2 splits

c) Single O and O2 combine

3) Located in a thin layer4) Blocks UV-b and UV-c5) 3mm thick (hole is 1mm thick)6) CFCs

Ozone and ultraviolet light

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All of C is absorbsMost of B is absorbedA little of A is absorbed

4. Height & Structure of Atmospherea. No distinct line b/w space and atmosphereb. Atmosphere thins until there is no more gas detected

c. Atmospheric pressure

1) Weight of the air above you2) Decreases as

with altitude

d. Temperature change1) Troposphere

a) Bottom layerb) Temperature decreases with altitudec) Almost all weatherd) Temp drops until tropopausee) 7.5 miles

2) Stratospherea) Temperature increases with altitudeb) Contains ozonec) Ozone heats up from absorbing UVd) Jets fly here

3) Mesospherea) Temp decreases with altitudeb) Approaches about -130˚Fc) Meteors burn up

4) Thermospherea) Upper layer with no defined limitb) Temp increases w/altitudec) O2 and N2 are absorbing solar

radiationd) Northern lights (ionosphere)

5. Earth-sun Relationships a. Earth’s motions

1) Rotationa) Spinning on axisb) Spins once every 24hrs

2) Revolution a) Movement of earth in orbitb) 70,215 mph

b. Earth’s Orientation1) Tilted 23.5˚2) Causes seasons3) Pointed at Polaris

c. Seasons1) Summer Solstice

a) First day of summerb) Axis is leaning towards the sunc) June 21 or 22d) Longest day

2) Winter Solsticea) First day of winterb) Axis leaning away from the sunc) December 21 or 22d) Shortest day

3) Autumnal equinoxa) September 22 or 23b) Start of Fallc) Day and night are equal lengthd) Not tilted towards or away from the sun

4) Spring equinoxa) March 21 or 22b) Start of Springc) Day and night are equal lengthd) Not tilted towards or away from the sun

B. Heating the Atmosphere1. Energy transfer as heata. Heat – energy transfer

from one object to another b/c difference of temperatures

b. Temperature – average amount of kinetic energy in individual atoms of a substance

c. Conduction1) Heat transfer through matter

by molecular activity2) Transfers from high temp to low temp3) Metals good

conductors, air is not

d. Convection1) Transfer of heat by mass movement

or circulation within a substance2) Oceans and air3) Warm things expand and become less dense4) Water rises, cooler water sinks

Convection currents in mantle

Sea and Land Breeze

e. Radiation1) Only one to travel through a vacuum

(doesn’t need a medium)

2) Hotter objects radiate more energy

2. What happens to solar radiationa. Energy is absorbed – converts energy

to heatb. Transmitted

1) Energy is not transferred or converted2) Air and water

c. Energy bounces off – not absorbed or transmitted

d. Reflection and Scattering1) Reflection – light bounces off an object2) Scattering – produces larger number of rays that go in different directions

e. Absorption1) Crust heats up and sends heat into air2) Atmosphere traps this b/c it has longer

wavelengths than from the sun3) Greenhouse effect (H2O & CO2)

C. Temperature Controls1. Why temperatures varya. Land and Water 1)Land heats up and cools down faster2)Land can reach hotter and colder temps

compared to water3)Temperature ranges are greater over

land

LAND VS. WATER

Both have the same latitude to control variables- Same length of day- Same angle of sun’s rays

b. Geographic Position1) Windward – wind blows from ocean to shore2) Leeward – wind blows from land to ocean

Spokane is cut off by Cascade Range◦Seattle has marine

weather◦Spokane has continental

weather

c. AltitudeFigure 18 pg 491

d. Cloud Cover and Albedo1) Albedo – how much radiation is

reflected by a surface2) Clouds have a high albedo3) Cloudy days

a) Cooler temperaturesb) Block radiation

4) Cloudy nightsa) Warmer temperaturesb) Trap radiation/heat