Sem#2 Chap 1 Flashcards
Air
A mixture of gases surrounding the earth.
Includes carbon dioxide and hydrogen
99.9% of earths air is within _____ of the earths surface? (in km)
0-50km
Wind
The horizontal movement of air
Percipitation
Water falling from the sky. Liquid or solid
Storms
When wind and precipitation are dangerous
Atmospheric Hazards, examples
Blizzard and Hurricane
Water Vapor (not exactly a definition)
Percentage varies depending on time and place.
Constantly changes phase to liquid and solid.
Aerosols
Liquid or solid particles
Dust, soil, salt, ash, pollen, bacteria mold.
Creates haze when present with water vapor.
Sizes of water particles in air
Water molecule: 0.0000003
Aerosol: 0.0004–0.01
Cloud droplet: 0.01–0.1
Drizzle: 0.1–0.5
Small raindrop: 0.5–1.0
Large raindrop: 1.0-4–0
Very large raindrop: 4.0–8.0
Clouds
Clouds consist of water droplets
Clouds consist of ice crystals
Air Pollution is and is caused by
Anthropogenic gases and aerosols create polluted air.
Primary Pollutants
Emitted directly from a source
Examples: Vehicle exhausts and industrial processes.
Secondary Pollutants
When primary pollutants react together with sunlight.
Examples: Ozone and Acid rain
Pollution in the late 19th century was____ (mainly consisted of)
Smog:
Soot, Carbon monoxide, and sulfur bearing gases.
Pollution today is called _____
Photochemical Smog:
When primary pollutants react with other gases and sunlight.
Examples: Ozone and Nitric acid aerosols
Class Question #1
What was the societal impact of the smog event experienced in London,
December 5–9, 1952?
a) The city mandated that scrubbers be placed on all industrial
smokestacks.
b) A pollution tax was created, thereby increasing the cost of petrol
and electricity across London.
c) Over 6,000 people died.
d) An executive order from the mayor created even/odd driving days,
based on a vehicle’s license plate number.
(No given answer)
Weather
Specific atmospheric conditions at a time and place.
Meteorologists study and predict weather
Climate
Average weather conditions over many decades.
Climatologists study and predict climates.
Atmospheric conditions describing weather:
- Temperature: the air’s hotness or coldness
- Pressure: the weight of air above a location
- Relative humidity: the presence of water vapor
- Wind direction: the compass direction from which the air moves
- Wind speed: the velocity of air’s horizontal movement
- Visibility: a measure of how far one can see through the air
- Cloud cover: the portion of sky covered by clouds
- Precipitation: the amount of water and/or ice falling to the ground
Temperature:
Air molecules average speed.
Kinetic energy of air molecules.
KE = MV^2
Thermal Energy
The sum of all kinetic energy in a material
Heat
When thermal energy is transferred.
Always flows from hot to cool materials
Atmospheric Pressure
The force applied by air on a specific surface area.
The weight of a column of air.
With no wind, air pressure is the same in all directions.
Molecules move ______ in hot air. And hot air is _____.
apart, less dense
Molecules move ______ in cold air. And cold air is _____.
closer together, denser
Air pressure varies how often?
Daily and seasonally
Air pressure and density
decrease as altitude ______.
increases
Vapor pressure
The portion of air pressure exerted by water vapor.
At a specific temperature:
Dry air has a ______ vapor pressure.
Moist air has a _______vapor pressure.
- Dry air has a lower vapor pressure.
- Moist air has a higher vapor pressure.
Saturated air:
- Contains all the water vapor it can hold
- Dictated by temperature and atmospheric air pressure
Saturation vapor pressure:
- The atmosphere’s vapor holding capacity
Relative Humidity
Measures how close the air is to saturation.
Determined by 2 variables:
* The amount of water vapor in the air
* The air’s vapor capacity (which is temperature dependent)
Air’s vapor capacity increases as temperature ________.
Increases
Relative Humidity (RH) formula
(vapor pressure / saturation vapor pressure) x 100
Dynamic Pressure
The stress caused by moving a fluid
Wind direction
the direction from where the wind blows
Wind speed
The horizontal rate of air movement
Wind bards
graphically display wind speed and direction.
Streamlines
graphically display wind as parallel lines.
Visibility
how far one can see through the air
Pure air is _______. (visibility wise)
Transparent
Cloud cover
the proportion of the sky containing clouds
Precipitation rate
how fast precipitation occurs (mm/hr)
Total precipitation
cumulative amount during a time period
Total snowfall
accumulated depth or water equivalent
Radar systems transmit pulses of _____.
microwaves,
Microwaves return to antenna after
hitting rain and hail.
Microwaves travel at _______.
Speed of light
Radars can also measure ______
Altitude of rain and hail
Radar reflectivity
the strength of the returned signal
High reflectivity
heavy rain
Low reflectivity
Light drizzle
Thermometers measure ______.
air temperature
Barometers measure ______.
air pressure
Anemometers measure ______.
wind, speed, and direction.
Hygrometers measure _______.
relative humidity
Rawinsondes measure _______.
Temperature, moisture, and wind measured
lifted to 20 km by
weather balloons
Satellites display _______.
cloud cover
Class Question #2
A meteorology statement reports the wind as “southeast at 10 mph,
gusting to 15.” From what direction is the wind blowing?
a) from the northwest
b) from the northwest at 10 mph, then from the southeast at 15 mph
c) from the southeast at 10 mph, then from the northwest at 15 mph
d) from the southeast
(no given answer)
Atmospheric temperature
changes with _______.
altitude
Lapse rate
the change of temperature with altitude
* ~6.5°C/km
Troposphere is heated by ….
- Heated by infrared radiation from Earth’s land and water
Stratosphere: Is heated by ….
- Heated by ozone (O3) absorbing ultraviolet light
Mesosphere is ______ due to lack of ozone
cools due to lack of ozone (O3)
Thermosphere
high-energy radiation absorbed by gases
Clouds form when ….
saturated air becomes supersaturated.
- Water condenses on aerosol
condensation nuclei. - Water freezes on aerosol ice
nuclei.
Supersaturating processes:
- Warm air flowing up and over cooler, dense air
- Air forced to rise over a mountain
- Warm, buoyant air rising and cooling at high elevation
Cirrus
high and wispy
Stratus
cover broad areas
Cumulus
tall, puffy, and cauliflower-like
Nimbus suffix
clouds that produce precipitation
Cirro prefix
high-altitude; Alto prefix: intermediate altitude
(Simply meaning high clouds)
Fog
is a cloud at ground level.
Raindrops grow as they fall because, ____
by colliding with other droplets
Warm clouds have …. (temperatures)
consistent temperature > 0°C.
Cold clouds have ….
consistent temperature < 0°C.
Ice crystals may grow in 2 ways:
- Snowflakes: when liquid water gradually freezes to ice nuclei
- Rime: when supercooled droplets instantly freeze to ice nuclei
Graupel and hail develop when ….
rime ice crystals keep growing
Phase change
when H2O changes state.
Phase change always absorbs or
releases energy.
Latent heat
energy absorbed or released during phase change
Latent heat does not change ______
H2O temperature.
Latent heat only changes ________
H2O state.
Latent heat is released when _____
H2O condenses and/or freezes
Latent heat is absorbed when _______
H2O melts and/or evaporates.
Jet stream
high-altitude air blowing at 90-400 km/hr
Pressure gradient
pressure change divided by distance.
* Air always moves from higher to lower pressure.
Pressure gradient is represented on maps with ______
isobars
Isobars
lines along which all points have the same pressure.
Pressure gradient force (PGF):
the force causing air to flow.
- Narrowly-spaced isobars = larger PGF, faster winds.
- Widely-spaced isobars = smaller PGF, slower winds.
Friction reduces air speed, occurs when ….
- Occurs when molecules collide with other molecules.
- Occurs when air shears against Earth’s surface.
- Boundary layer
the layer of air where friction affects air flow.
Coriolis Effect:
- Air’s apparent deflection relative to the spinning Earth
- Air veers right in N hemisphere, left in the S hemisphere.
Coriolis Effect increases as ______
air speed increases.
Surface Heating and Low Pressure causes: (List)
Air at Earth’s surface expands and rises with local heating.
Rising air flows up air column.
Isobaric surfaces bend upward as air rises.
Mass of air column decreases.
A surface-bound low-pressure area develops.
Surface Heating and High Pressure creates: (List)
Air at Earth’s surface contracts and sinks with local cooling.
Sinking air flows down air column.
Isobaric surfaces bend downward as air sinks.
Mass of air column increases.
A surface-bound high-pressure area develops
Wind direction’s 3 variables:
- Pressure gradient force
- Coriolis force
- Friction
Northern hemisphere low pressure:
- Wind spirals into a low pressure, counterclockwise.
Northern hemisphere high pressure:
- Wind spirals out of a high pressure, clockwise.
Geostrophic Balance
When PGF and Coriolis effect are balanced
No friction at high elevations
Air flows parallel to isobars
Class Question #3
What is the pressure gradient force (PGF) for the following scenario?
* Air pressure at city A: 988 mb
* Air pressure at city B: 1,000 mb
* Distance between cities A and B = 250 km
a) 0.048 mb/km
b) 20.83 mb/km
c) 12 mb/km
d) 1.78 mb/km
a) 0.048 mb/km
The tropics
between latitudes 23.5°N and 23.5°S
* Tropic of Cancer (23.5°N)
* Topic of Capricorn (23.5°S)
* Rainforests are common.
The subtropics
between 23° and 35°, N and S latitude
* Grasslands, deserts, and steppes are common.
Global air circulation is
driven by ______.
solar heating
Hadley cells are
density-driven convection flows:
- Tropical air warms, rises, and flows toward poles.
- Subtropical air cools, sinks, and flows toward equator.
Circulation controls rainfall distribution in low latitudes
Trade winds
result as Hadley cell air flows toward equator:
- Northern hemisphere surface winds curve southwest.
- Southern hemisphere surface winds curve northwest.
Intertropical Convergence Zone (ITCZ):
- Where N and S hemisphere trade winds converge
- Shifts N of equator during N hemisphere summer
- Shifts S of equator during S hemisphere summer
Walker Circulation
An east-west flowing convective cell in the equatorial Pacific
Walker Circulation Normal Pattern
Normal pattern:
* Air warms and rises to tropopause over W Pacific.
* High-altitude air flows east, then cools and sinks over the E Pacific.
* Surface air flows west, over ocean, to W Pacific.
La Niña (Not the cycle)
a very strong Walker circulation pattern
Look at slide 47
wdwdwdwd
El Niño:
- Oscillation often occurs around Dec. 25th.
- Spanish for little boy, meaning Christ Child
ENSO: El Niño/Southern Oscillation
Look at slide 50
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Monsoons
A seasonal reversal in wind direction
Wind reversal causes shift in precipitation.
Monsoons exist where winds blow over both sea and land.
Summer Monsoons (Slide 53)
Summer (rainy season): wind blows from ocean to land
* Air over land warms faster than air over ocean.
* Low pressure develops over land.
* Higher pressure, moist air over ocean flows toward land.
Winter Monsoons (Slide 54)
Winter (dry season): wind blows from land to ocean
* Air over land cools faster than air over ocean.
* High pressure develops over land.
* High pressure, dry air over land flows toward ocean.
Class Question #4
Why do Peruvian fishermen prefer La Niña over El Niño?
a) Because La Niña blows surface water, and thus fish, closer to the
Peruvian coast.
b) Because La Niña creates nutrient-rich water off the Peruvian coast.
c) Because La Niña’s heavy rains create freshwater runoff, which
fertilizes Peruvian fisheries.
d) Because the Intertropical Convergence Zone (ITCZ) weakens during
La Niña, thereby enhancing fish habitats in Peru.
(No given answer)
Mid-latitudes: Angle and Explination
30°–60°
- A temperate climate with daily and seasonal weather changes
High-latitudes: Angle and Explination
> 60°
- A polar climate with temperature near or below freezing
Air masses
- Large bodies of air with uniform temperature and humidity
- Several kilometers thick, >1,000 km across
- Often cover half a continent or ocean
Air mass classification
- Source region: either continental (dry) or maritime (humid)
- Temperature: either tropical (warm) or polar (cold)
Cold air masses are what type of system?
typically high pressure systems
Warm air masses
typically low pressure systems
Cold front: (Slide 60)
- Cold air mass advances under a warm air mass.
- Warm air is forced to rise, thunderstorms are common.
- Represented by a blue line with triangles
Warm front: (Slide 61)
- Warm air mass advances while cold air mass retreats.
- Represented by a red line with semicircles
Occluded front: (Slide 62)
- Advancing cold front overtakes a retreating warm air mass.
- Represented by purple triangles and semicircles
Stationary front: (Slide 63)
- A static boundary between a warm & cold air mass
- Cold air flows parallel to front, warm air rises over cold air.
- Represented by blue triangles and red semi-circles
The Polar Front and Jet Stream
The boundary between warm, tropical air and cold, polar air
* Marked temperature differences are common.
* Temperature difference creates stark isobaric surface contrasts.
Steep pressure gradient generates polar-front jet stream:
* Very fast wind, 10 km high, flowing over the polar front
* Flows in wave-like undulations
* Ridge: a region where jet stream bows toward the poles
* Trough: a region where jet stream bows toward the equator
Divergence:
an air deficit at the tropopause
* Creates low-pressure center
* Surface air rises into low pressure center.
Mid-Latitude Cyclone Evolution: Part 1
Warm front extends eastward of low-pressure center.
Cold front extends from the center toward the south or southwest.
Warm air south of the warm front flows up and over warm front.
Warm air east or southeast of cold front undergoes lifting.
Mid-Latitude Cyclone Evolution: Part 2
Surface air spirals counterclockwise into low-pressure center.
Warm front slowly migrates northward.
Mid-Latitude Cyclone Evolution: Part 3
Cold front progressively wraps around the low-pressure center.
Cold front begins to catch up with warm front.
Mid-Latitude Cyclone Evolution: Part 4
Occluded front forms.
Cool air north of the warm front undergoes lifting.
Uplifted warm air overlies both cold air masses.
A Mid-Latitude Cyclone Characteristics
Maximum intensity within
~48 hours of initiation
* Maximum intensity may last
~2 days.
Entire system may evolve
and last over a week.
* Strong counterclockwise
surface winds
* Broad areas of cloud cover
and precipitation
Shaped like a giant comma
Head of comma:
* Blizzards and ice storms
Tail of comma:
* Thunderstorms, tornadoes,
and windstorms
Mid-Latitude Cyclone Weather
Different types of hazardous
weather are common.
Different geographic regions
experience unique impacts.
Comma head and comma tail
deliver very different effects.
Class Question #5
Select the two defining characteristics of a continental polar air mass.
a) dry and warm
b) dry and cold
c) moist and warm
d) moist and cold
(No given answer)
