Transcript Meteorology Part 1

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
METEOROLOGY PART 1
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
ASH
Carbon
MICROBES
Dioxide
CRYSTALS
ARGON
Ca
Nitrogen
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
CLOUDS & FOG
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)
above
surface 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