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METEOROLOGY PART I
Name:
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)
Argon
Carbon Dioxide
All Others
OXYGEN (O2)
ARGON (Ar)

Compounds: CARBON DIOXIDE (CO2)
Oxygen
WATER (H2O)
OZONE (O3)
absorbs harmful UV RAYS (ultraviolet)

Nitrogen
Atmospheric Dust: SOIL
ASH
MICROBES
CRYSTALS
ATMOSPHERIC PRESSURE

Gravity that is PULLING particles TOWARD EARTH

Ratio of:

Measuring Device for Atmospheric Pressure: BAROMETER (p.532)
air weight
.
surface area on which it presses
o Atm.Pressure measured in N/m2.
o 1 Atm = 760 mmHg

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 Layering is caused by TEMPERATURE differences.
MESOSPHERE
ALTITUDE (Miles)
ALTITUDE (Km)
THERMOSPHERE
STRATOSHPERE
MAXIMUM OZONE
TROPOSPHERE
TEMPERATURE
Atmospheric Layers
(1) TROPOSPHERE
 Closest to earth
 Holds the most CO2 and H2O vapor
 All WEATHER changes happen here
 Temperature ↓ as altitude increases.
o 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.
o Why? CLOSER TO O3 LAYER WHICH
ABSORBS UV LIGHT & HEAT
(3) MESOSPHERE
 From stratopause to 80km in altitude
 Coldest layer
 Temperature ↓ as altitude increases.
o Why? FARTHER FROM O3 LAYER
(4) THERMOSPHERE
 From mesopause to outer space
 Temperature ↑as altitude increases.
o Why? OXYGEN AND NITROGEN
ABSORB SHORT-WAVE, HIGHENERGY SOLAR RADIATION

Two layers:
o IONOSPHERE - lower layer.
Holds electrically charged particles.
o 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.
CHAPTER 18: Moisture, Clouds & Precipitation
Atmospheric Moisture
~Section 18.1~
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: GASSES 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.
(page483)
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Cloud Terms
Cloud Formation = from CONDENSATION of water vapor over a large area of air.
STRATUS = sheetlike or layered
NIMBUS / NIMBO = rain
CUMULUS = piled or heaped
ALTO = middle altitude
CIRRO / CIRRUS = curly, high altitude
FOG = clouds near the Earth’s surface
-------------------------------------------------------------------------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.
PRECIPITATION
~18.3~Pages 520-522~
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
CYCLONE
TYPE
DIAGRAM
CHARACTERISTICS
(In the Northern
hemisphere)
* Winds blow counterclockwise
* Net flow of air inward at the
surface
LOW
(Cyclones)
HIGH
(Anticyclones)
EXPECTED
WEATHER
* Cloudy
conditions
Pressure decreases
from the outside
towards the center
* Precipitation
* Rising air
* Produces violent
storms if the Low
pressure system is
strong enough
* Winds blow clockwise
* Fair weather
* Net flow of air outward at the
surface
* Clear skies
* Sinking air
AIR PRESSURE
Pressure increases
as you move from
the outside toward
the center
ISOBARS = lines that
connect points of equal
air pressure
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) above
surface anticyclones
METEOROLOGY PART II
Name:
Convection & Global Winds
~Section 19.2~
Recall:

Warm Air RISES, and Cool Air SINKS.

At low altitudes, air pressure is HIGH. At high altitudes, air pressure is LOW.
So….. in a giant convection cell…
1. At the equator, air becomes WARMER and RISES to an area of LOWER pressure.
2. The LOW pressure causes the air to EXPAND, moving it toward the POLES.
3. Next, the air COOLS and SINKS back to the earth.
4. Finally, the air will move toward the EQUATOR, where the cycle begins again.
Why doesn’t the air actually move this way?
BECAUSE THE EARTH ROTATES TOWARD THE EAST.
The resulting wind movement is called the CORIOLIS EFFECT.
HOW DO THESE CONVECTION CELLS
RELATE TO BIOMES?
THE LOW PRESSURE SYSTEMS
GENERALLY HAVE RAINY WEATHER.
TROPICAL RAINFOREST
& TEMPERATE RAINFOREST
EXISTS @
0°, 60°N, 60°S
THE HIGH PRESSURE SYSTEMS
GENERALLY HAVE CLEAR WEATHER.
DESERT
& TUNDRA
EXISTS @
30°N, 30°S, 90°N, 90°S
**NOTE: ---Wind speed is measured using an ANEMOMETER
---Wind direction is measured using a WEATHER VANE
JET STREAMS!!

Wind caused by TEMPERATURE and PRESSURE differences

Jet Stream: narrow bands of FAST, high-ALTITUDE, WESTERLY winds.
o Speed: up to 185 km/hr
o Altitude: 10.7 km to 12.2 km

Resemble JETS of WATER

2 types:
* POLAR = stronger of the two
* SUBTROPICAL = controls much of
the weather in the US
Air Masses
~Section 20.1~
AIR MASSES: an immense body of air that is characterized by similar temperature & moisture.
- can be 1,600 km or more across… take several days to move over an area
- When an air mass moves out of the region over which it formed, it carries its temp & moisture
- The characteristics of an air mass change as it moves and so does the weather in that area
- Air masses are classified according to the surface over which they form
FRONTS
~section 20.2~
 Front: narrow region separating 2 air masses of different densities
 Air masses collide forming _fronts_. Fronts can cause dramatic __changes__ in weather.
 4 Types: _cold , __warm__, ___stationary__, and __occluded___
1) COLD FRONT

Cold, dense air displaces ___warm___ air, forcing the warm air _up__.

Warm air _rises _, cools, and _condenses_

Forms __clouds__, __showers__, and sometimes __thunderstorms_____

__Fast__ temperature change: air gets __colder__.

Advance more ___rapidly___ than a warm front.

SYMBOL: Color? Direction of Movement?

DIAGRAM:
2) WARM FRONT

Advancing _warm___ air displaces __cold___ air, and the warm air rises above the cold air.

Extensive _cloudiness__ and ___precipitation____

__Slow__ temperature change: air gets __warmer__.

SYMBOL: Color? Direction of Movement?

DIAGRAM:
3) STATIONARY FRONT

Warm and Cold air meet, but neither moves into the other’s territory, which __stalls__ the front.

They stall because the ___temperature__ and __pressure___ gradients are small.

SYMBOL: Color? Direction of Movement?

DIAGRAM:
4) OCCLUDED FRONT

A cold air mass moves so rapidly that it __overtakes a warm front____.

The cold air masses collide, pushing the warm air ___upward____.

Causes

SYMBOL: Color? Direction of Movement?

DIAGRAM:
BEFORE
precipitation on both sides of the front_______.
DURING
AFTER
Severe Storms
~section 20.3~
Thunderstorm
Tornado
Lightning
A
B
C
Hurricane