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Clouds
are of the atmosphere that's saturated or supersaturated, millions or billions of microscopic size water droplets
Warm clouds
Temp of environment is > -10 degrees C -consist exclusively of water droplets (water has hard time freezing in thin air)
Cold Clouds
temp of environment is < -10 degrees C -consist largely of ice crystals
Clouds distinguished on basis of...
-altitude - pattern - ability to produce precipitation
height
cirro- high level clouds alto- mid-level clouds - largely cold
Pattern
cumulo- vertically developed -associated w/ convection strato- stratified -featureless, no vertical development -cold and warm clouds
Precipitation
nimbo- precipitation bearing - cold and warm clouds
Cirrus
thin, wispy clouds At least 18,000 ft. in atmosphere ALWAYS below -10 C Most common are cirrus Not very dense or thick
Cirrocumulus
high level -little bit of vertical development *fine grained pattern, tiny patches of blue sky in btwn tiny clouds - indicates there's some instability there (vertical motion--> cloud)
Cirrostratus
typically cover most or large amount of sky thin low density sun can shine through Sometimes create ring around sun/moon ("sun dogs": pattern where like is diffracted into diff colors )
Contrails
Commercial airlines create these (20,000-40,000 ft.) "con"= condensation water vapor out of plan creates deposition (vapor--> ice crystals) -Esp. common in Midwest -makes it less likely to cool down at night -more common in winter
Altocumulus
vertical development (similar to cirrocumulus) slightly larger than cirrocumulus -seems bigger b/c closer to the observer -Convection -Air sinks in blue patches of sky
Altostratus
VERY similar to cirrostratus Not very thick, sun can shine through Sun is much dimmer coming through these clouds Little more density than cirrostratus (more ice crystals) *Gradual lowering of clouds
Status clouds
can produce drizzle, not measurable not very thick, usually thick enough to block out sun completely
Nimbostratus
Usually darker (b/c thicker) featureless as falling precipitation obscures cloud edges thicker stratified clouds little darker than stratus clouds less sunlight can come through
Stratocumulus
air that rises convectively, lifts and can't lift anymore so it sinks some -layered clouds, look little like cumulus clouds
Cumulus
• Common with daytime heating when the relative humidity is relatively high (e.g. summer in the Carolinas). -Rise a bit higher than other cumulus clouds -Clear indication of convection, instability in atmosphere -Esp. common during day (like in afternoon hours, b/c it’s the warmest so…
Cumulonimbus
-Keep developing and getting taller until they transition into a cumulonimbus clouds -Very little light can get through it -After gets to tropopause (temp starts to get warmer (inversion))- atmosphere becomes very stable (loses buoyancy)à spreads out (creates anvil, elliptical or circula…
Super cell storm
rotating
Precipitation
• Requires the development of droplets/snowflakes that are 100 times bigger than cloud water droplets/ice crystals Need saturated environment sustained enough lifting (so droplets/crystals can get big enough to form rain/snow) Cloud water droplets much smaller than raindrops (must gro…
Bergeron
grows ice crystals through multiple processes involving all 3 states of water -requires a cold cloud SEE CHART in powerpoint
Air Pressure (P)
force exerted by air across a unit area measured by Barometer
Isobar
line on weather map that connects points that have the same atmospheric pressure -low & high pressure systems tell us what weather will be like -close together= rapid changes in air pressure, very windy -far apart: lighter winds
Low pressure systems assoc. w/
inclimate weather Cyclone: converging toward lower pressure -counterclockwise winds rising --> clouds, precipitation
high pressure systems assoc. w/
inclimate weather Cyclone: converging toward lower pressure -counterclockwise winds rising --> clouds, precipitation
Density
mass/volume - amount of mass contained in a given volume of a substance -smaller volume- molecules hitting each other more--> higher density
Temperature
in a confined space v= constant not constant in atmosphere in ideal gas law: inc. temp--> inc. pressure (& opposite)
Compressing/ expanding atmosphere
gets cooler-->contracts warmer--> expands warming column: bottom will dec. in air pressure, top will increase in air pressure in cooling column: increase in air pressure at bottom, top decrease in pressure
Relationship between temp and surface pressure
negative Day: warmer Night: cooler
Relationship between temp and pressure aloft
positive Day: air pressure higher aloft Night: air pressure at surface increase
Warm & Cold air column chart
SEE CHART
Monsoon
very wet season followed by a very dry season
Sea-land breeze
day: land warms faster than water, higher pressure over the water (wind from ocean-->land) --brings lot of moisture--> it's convected Night: water warmer, land higher pressure (win from land--> ocean)
Valley-mtn breeze
from valley up into the mountains happens during the day n this picture air rising- lower pressures on mountains (cumulus clouds form over mtns) Mtn breeze- men into valley happens at night air is pulled down the mtn slope (gravity) valleys very cold at night
Pressure gradient PG
affects wind primary factor (really generates the wind) -gradient- change in a quantity per unit in a distance - as PG increases, the wind speed increases -usually in mb/ 100 km -tornadoes have strongest pressure gradient in weather
Coriolis Effect
- moving objects to turn towards the right (left) in the Northern (Southern) Hemisphere. -stronger in higher latitudes
Geostrophic wind
wind that blows parallel to isobars, well above the earth's surface -surface complicates the wind (trees, buildings, etc. slow the winds down, decreases Coriolis effect)
Friction
resistance to air flow associated w/ surface roughness
gust factor
low gust factor- very consistent winds
wind fetch
distance over which winds can blow unimpeded
Bernoulli effect
the fact that winds can funnel their way through narrow passages wind gap: winds funnel through the gap, blow faster Bernoulli effect
pollutant
airborne particles and gases that occur in concentrations that endanger the health and well being of organisms ex. dust, volatile organic compounds (VOCs) from vegetation (ex. haze in smoky mtns) sulfur dioxide from volcanoes
Primary pollutants
released directly from the surface
secondary pollutants
chemical reactions w/ primary pollutants *summer: lots of ozone created in atmosphere (made during day, max. in late afternoon)
Air pollution trends
downward air cleaner now than used to be EPA, filters, more efficient cars Average globally: much higher (China, India)
Air pollution sources
concentrated in red areas of map (SEE MAP) scattered across south
wind speed weakest
night or early morning (faster during cool season, March windiest month) Winds move downstream and spread out (disperse)
subsidence inversion
broad areas of atmosphere wind is sinking (warming up) -reaches point and can't sink anymore -Much higher than nocturnal radiation inversion
Bermuda High
largely responsible for mid-level subsistence in the Carolina
Adiabatic processes
change in temp of air, no addition or subtraction of heat
Lifting Condensation level (LCL)
height that air must be lifted in which to bring it to saturation -marine environment: don't have to lift very much, so lower LCL's -increases throughout day -slightly higher over cities vs. rural areas
Convective Uplift
buoyant air parcels rise as they remain relatively warmer ( & less dense) than their surroundings -almost every day it's sunny this occurs - usu. happens on sides of lake (b/c air over water is cooler and isn't rising)
Instability
has propensity for convection to occur
What is stability based on?
the lapse rates
Environmental Lapse rate (ELR)
the rate of change of temperature w/ height in the atmosphere -always changing -varies w/ space & time -varies according to weather features in the area (ridges, troughs, clouds, etc.)
Dry adiabatic lapse rate (DALR)
rate of change of temp in a rising DRY air parcel -usually around 10 degrees C
Wet adiabatic lapse rate (WALR)
rate of change of temp in a rising SATURATED air parcel -usu. 5-6 degrees C

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