Warm Up 1. At 25 0 C, air contains 15 gH 2 O / m 3 air. Saturation point: 20 g/m 3 Calculate the relative humidity. 2. What is the dry adiabatic rate?

Warm Up

1. At 250 C, air contains 15 gH2O / m3 air. Saturation point: 20 g/m3 Calculate the relative humidity.

2. What is the dry adiabatic rate?3. How does the temperature change

within the thermosphere?

WARM UP

1. What is the most abundant gas in the atmosphere?

2. What causes different layers in the atmosphere to form?

3. What is used to measure atmospheric pressure?

4. Where is the ozone layer located?

Chapters 17 and 18

Chapter 17: Atmosphere

ATMOSPHERE - layer of gases and tiny particles surrounding the earth

WEATHER - general atmospheric conditions at a particular time and place

CLIMATE - general weather conditions over many years

Composition of the Atmosphere Elements: NITROGEN (N2)

OXYGEN (O2)

ARGON (Ar) Compounds: CARBON DIOXIDE (CO2)

WATER (H2O)

OZONE (O3) absorbs harmful UV RAYS (ultraviolet)

Composition of the Atmosphere Atmospheric Dust: SOIL

ASHMICROBESCRYSTALS

Ca Carbon Dioxide

Nitrogen

ARGON

All Others

Oxygen

Atmospheric Pressure

Gravity that is PULLING particles TOWARD EARTH

Ratio of: air weight . surface area on which it presses

Measuring Device for Atmospheric Pressure: BAROMETER (p.532) Atm.Pressure measured in N/m2. 1 Atm = 760 mmHg

Atmospheric Pressure

Δ Pressure: Higher altitude = FEWER gases = LOWER pressure

Lower altitude = MORE gases = HIGHER pressure

Δ Temperature: Higher altitude = LOWER pressure = LOWER temperature

Lower altitude = HIGHER pressure = HIGHER temperature

Atmospheric Layers

Atmospheric Layering is caused by TEMPERATURE differences.

Atmospheric Layers

(1) TROPOSPHERE Closest to earth Holds the most CO2 and H2O vapor All WEATHER changes happen here Temperature ↓ as altitude

increases. Why? FARTHER FROM THE HEAT

ABSORBED BY EARTH

2) STRATOSPHERE From tropopause to 50km in

altitude Includes the OZONE LAYER (O3)

Temperature ↑ as altitude increases. Why? CLOSER TO O3 LAYER WHICH

ABSORBS UV LIGHT & HEAT

3) MESOSPHERE From stratopause to 80km in

altitude Coldest layer Temperature ↓ as altitude

increases. Why? FARTHER FROM O3 LAYER

(4) THERMOSPHERE From mesopause to outer space Temperature ↑as altitude

increases. Why? OXYGEN AND NITROGEN

ABSORB SHORT-WAVE, HIGH-ENERGY SOLAR RADIATION

Two layers: IONOSPHERE - lower layer.

Holds electrically charged particles. EXOSPHERE - upper layer.

Holds light gases (helium/hydrogen). No clear boundary between exosphere and space… Air gets thinner and thinner until you’re in outer

space.

Atmospheric Moisture

3 forms of water: ICE, LIQUID, or WATER VAPOR (most is in VAPOR form)

Phase Changes: HEAT energy causes an INCREASE in molecular motion.

*Motion causes molecular COLLISIONS and energy transfer.

Evaporation: molecules speed up and change from a LIQUID to WATER VAPOR

Condensation: molecules slow down and change from a GAS to a LIQUID.

Sublimation: SOLIDS change directly to a GAS. (Ex: DRY ICE)

Deposition: GASES change directly to a SOLID. (Ex: FROST)

Humidity = AMOUNT OF WATER VAPOR IN AIR SATURATED = air contains all of the

water vapor it can hold. When saturated, WARM air can hold

more water vapor than COLD air. Measuring Devices: HYGROMETER or

PSYCHROMETER

Specific Humidity = ACTUAL amount of moisture in the air. (Grams H2O / kg air)

Relative Humidity = percent mass of water vapor compared to mass water vapor at saturation.

Ex: At 200 C, air contains 14.3g H2O / m3 air. Saturation point: 17.1 g/m3

Specific Humidity: 14.3 g/m3

Relative Humidity: 14.3 g/m3 = 84% Relative Humidity

17.1 g/m3

Dew Point = TEMPERATURE to which the air must be cooled to reach saturation.

Depends on Relative Humidity. When temp. is below Dew Point:

CONDENSATION (dew) or DEPOSITION (frost) occur

Temperature Changes occur in 3 ways: CONDUCTION: Transfer of heat through matter by molecular activity. CONVECTION: transfer of heat by mass movement or circulation within a

substance. RADIATION: transfer of heat through matter or a vacuum by electromagnetic

waves.

Section 18.2

Cloud Formation = from CONDENSATION of water vapor over a large area of air.

Land/Sea Breezes Why does Winnipeg’s temperature

vary so much more than Vancouver’s?

Vancouver is near the large ocean, which heats/cools slower than land. It holds that heat easily, keeping Vancouver’s air from fluctuating significantly.

How do clouds affect Earth’s temperature during the day? Why?

Clouds reflect light away from the ground, keeping the temperature lower.

How do clouds affect Earth’s temperature during the night? Why?

Clouds insulate the air, keeping heat from escaping, keeping the temperature higher.

Types of Precipitation

***The type of precipitation that reaches Earth’s surface is determined by the temperatures in the lowest few kilometers of the atmosphere.

Rain & Snow Sleet = small particles of clear-to-

translucent ice.

Glaze = A.K.A. “FREEZING RAIN” – rain is supercooled (below 0°C) & become ice when they impact frozen objects.

Hail = small ice pellets grow as they impact supercooled water droplets as they fall through a cloud. UPDRAFTS push them back up, so they can gain new ice layers.

PRESSURE CENTERS & WIND~section 19.2~ - Most common features on any

weather map & weather generalizations can be made using them

- Winds are influenced by pressure (pressure gradients) centers and the Coriolis effect

What goes in, must come out!!!! When there is a converging air mass at

the surface, it must be balanced by outflow

- a surface CONVERGENCE can be maintained if a DIVERGENCE occurs above the low at the same rate as the inflow below and vice versa.Air spreads out (diverges)

above surface cyclones and comes together (converges) abovesurface anticyclones

Weather Maps

ISOBARS = lines that connect points of equal air pressure Closely spaced lines indicate 2 things:

Strong pressure gradient High winds

ISOTHERM = lines that connect points of equal temperature