geog

further growth of crystals due to

collisions between falling crystals and drops

hail

concentric layers of ice build around graupel water accreting to graupel freezes, forming a layer hail begins to fall, updraft, repeat

mixing ratio

amount of water vapor (g) relative only to mass of dry air (kg).

saturation vapor pressure

- maximum amount of vapor that can exist at a given temperature temperature dependent (warmer air can hold more water vapor non linear increase

tornadoes

100-600m last 1m to 1 hour

deposition

Water vapor (gas) can change directly into ice or snow (solid)

mesoscale convective systems

A cloud system that occurs in connection with an ensemble of thunderstorms and produces a contiguous precipitation area on the order of 100 Km or more in at least one direction, and often last for several hours to a couple of days.

cloud properties

cloud top height/pressure cloud thickness cloud coverage

cloud to ground lightning

20% electrical discharge travels between the base of the cloud and the surface

how long does it take thunder to travel 1 kilometer

3 seconds (5 sec per mile)

ocean covers what percent of the earths surface?

70%

cloud to cloud lightning

80% occurring when voltage gradient overcomes the electrical resistance of the air

multicell storm

Cool downdrafts leaving a mature and dissipating storm may offer relief from summer heat, but they may also force surrounding, low-level moist air upward. Hence, dying storms often trigger new storms

low stratocumulus clouds

Generated by convection inside boundary layer Convection is driven by cloud-top longwave cooling and evaporative cooling

lake effect

Heat and moisture fluxes from warm lake enhance snowfall in downstream regions

sublimination

Ice or snow (solid) can turn directly into water vapor (gas)

nearly 75% or tornadoes form from

March to july when humid air is overlain by cooler drier air to cause strong vertical lift

steam fog

Mixing of warm, moist air with cold air Adiabatic process (no net change of energy) e.g., common when cold air move over warm lakes/streams in autumn

during evaporation:

Molecules escape into the overlying volume as water vapor

components of global water cycle

Ocean water Land soil moisture, rivers, snow cover, ice sheet and glaciers Sea ice Atmosphere water vapor, clouds, precipitation Water in biosphere (including human beings

precipitation fog

Rain occurs and some evaporates as it falls toward Earth Sometimes this will lead to saturation near surface and cause fog Adiabatic process

during saturation

There is an equilibrium between evaporation and condensation evaporation rate equals condensation rate

during condensation

Water vapor molecules randomly collide with the water surface and bond with adjacent molecules

processes of lightning formation

charge separation stepped leader return stroke dart leader

tornadoes often evolve through

a series of stages, from dust whirl to organizing and mature stages and ending with the shrinking and decay stages

small drop has

a sphere shape

collision coalescense

collector drops collide with smaller drops and merge with them if collector drop is too big compressed air beneath forces small drops aside after collector drop becomes large, super collects

thunderstorm size

about 10 km, last 10 minutes to a couple of hours

diabatic processes

add/remove heat conduction radiation

most clouds form as

air parcels in boundary layer that are lifted and cooled to saturation

mountains

air passes over mountains and causes wave and turbulence on other side

large soggy snowflakes are

associated with moist air near freezing

sleet

begins as ice crystals which melt into rain as they fall through the atmosphere. Before reaching the surface they solidify into a frozen state

air can be cooled down by

by radiation, evaporation of raindrops, melting of snowflakes, etc.

when air temp increases with height

called an inversion sound waves are refracted as they move

fog

can be considered a cloud with base at ground level air has either been: cooled to dew point had moisture added mixed with warm moist air 5 different types radiation advection upslope precipitation steam

tornado formation

can develop in any situation that produces severe weather process not well understood

H2O is unique because

can exist in all three statesCan change from any state to any other state. Latent heat is consumed or released in a phase change

desertification

caused mainly by human activities and climate change 1 bil people under threat

formation of supercell thunderstorms

change in wind direction and speed with increasing height creates spinning effect in lower atmosphere spinning horizontal vortex tubes created by windshear turn into a mesocyclone most strong and violent tornadoes form within this area of strong rotation

development of microburst

contact outburst cushion

downdrafts

cool down the environment generally the lower troposphere can cause signif damage

collision combined with riming and aggregation allow formation of

crystals large enough to precipitate within 1/2 hour of initial formation

absolute humidity

density of water vapor expressed in g/m3

when an air parcel rises, the cooling rate of the parcel relative to the cooling rate of the surrounding atmosphere...

determines the stability of the parcel

upslope fog

develops due to adiabatic cooling occurs when air is lifted over topographic barriers, mountains air expands and cools as it rises common in region between Great Plains and Rocky Mountain foothills

wall cloud

forms underneath the mesocyclone when cold/moist downdraft air feeds into the updraft and condenses at a lower level than warm air.

condensation/deposition forms

dew, frost, fog, clouds

lightening

discharge of electricity, giant spark

saturation forms

droplets or ice crystals

what stops unstable air masses from rising indefinitely

entrainment encountering a layer of stable air

mature stage

entrainment of dry air that causes cooler air from evaporation triggering downdrafts and falling precipitation and gust fronts

1st law of thermodynamics

expanding air cools, compressed warms

tornado outbreak

families of tornados

jet streams

fast, high altitude air currents

air that is cooler than its environment tends to sink leading to

formation of downdrafts

freezing rain

forms similarly to sleet, however, the drop does not completely solidify before striking the surface

why are clouds wildcards for climate change?

good reflectors of solar radiation (cooling) and absorbers of longwave (warming effect) difficulty simulating clouds especially stratocumulus

ozone named after

greek word for smell

downbursts

gusts of wind that can reach speeds in excess of 270 km/hr

thermals

heat from sun makes warm air masses rise and cold sink

runaway discharges

high speed moving electrons radiate light as lightning electrons approach speed of light when a large number of these happens its a runaway breakdown

saturation specific humidity

highest specific humidity for a given temperature and pressure

graupel

ice crystals that undergo extensive riming Lose six sided shape and smooth out Either falls to the ground or provides a nucleus for hail

cloud seeding

induce precipitation, injection of dry ice or silver iodide into clouds convert super cooled droplets to ice to initiate bergeron process

for a cloud drop to fall,

its terminal velocity must exceed the vertical velocity of the upward-moving air parcel. Otherwise it will be carried up.

aggregation

joining of ice crystals through the bonding of surface water builds ice crystals producing snowflakes

effects of supercell thunderstorms

large hails Damaging winds Deadly tornadoes Flooding Dangerous cloud-to-ground lightning

nitrogen cycle

lightning breaks nitrogen moleules and enables atoms to combine with oxygen in the air forming NITROGEN OXIDES dissolve in rain, carried to earth only source of nitrogen for early life forms

dew

liquid condensation on surface occurs early morning on windless cloudless days air immediately above ground cools, reaches dew point diabatic process

riming

liquid water freezing onto ice crystals

microburst

localized column of downdraft produces damaging divergent winds at surface similar to tornados dangerous to airports wet, dry, hybrid

specific humidity

mass of water vapor (g) per mass of air (kg) (in g/kg).

saturation mixing ratio

maximum mixing ratio

air parcels can be lifted by

mountains, meeting of different air masses, surface convergence, and local convection

wake turbulence

near ground a passing plane sets up chaotic currents

wet microburst

nearly saturated layer topped by dry layer driven by entrainment and precipitation loading heavy participation rain foot visible

adiabatic processes

no addition/removal of heat add water vap to air mix warm air with cold cooling of air parcel when rises

radiation fog

occurs when near surface air chills diabatically through loss of longwave radiation reaches Dew Pt requires cloudless nights and light wind to create mixed layer 'burns' off with sunrise - evaporates from below due to surface heating

advection fog

occurs when warm moist air moves across a cooler surface air is chilled diabatically to saturation common on the U.S. west coast warm, moist air from

snow

precipitation that forms by the Bergeron process, riming, and aggregation, and reaches the surface without melting

cloud drop growth is required for

precipitation to form

nitrogen oxides produced by lightening can react with others in the presence of sunlight to produce

ozone (doesnt really add to polution)

medium drop has

parachute shape

supercell storm

producing a minimum of ) 3/4 inch hail and/or wind gusts of 50 knots and/or tornado winds, classify as severe.

tornado

rapidly rotating column of air blowing around intense low pressure with circulation reaching ground wind between 105 km and 450 km

static stability

refers to atmospheres susceptibility to being displaced related to buoyancy force determined by density difference between parcel and environment

frozen dew

results when saturation occurs slightly above 0oC liquid dew formed, when Temp drops liquid dew freezes forms thin sheet of ice, tightly bound to surface dangerous - black ice

when convection happens

rising up of air parcel formation of clouds and rain heating up the environment because parcel is warmer than environment

suction vortices

small zone of intense rotation in most violent tornadoes

large drop

spherical with flattened bottom

trigger

start to uplift

thunderstorms

storm containing lightning and thunder convective (form when warm humid air rises in conditionally unstable environment)

haboobs

strong horizontal winds over desert regions create sandstorms

dew point temperature

temperature at which saturation occurs in air (generally colder than Tair, equals to Tair when saturated)

saturation vapor pressure of ice less than

that of super cooled water at the same temperature

relative humidity

the amount of water vapor in the air relative to the possible maximum.

vapor pressure

the partial pressure exerted by water vapor

collection efficiency is greatest when

the size of collector drop is slightly larger than the size of other drops

thunder

this rapid heating of air will creates an explosive shock wave

entrainment

turbulent mixing of ambient air into parcel leads to evaporation along cloud boundaries uses latent heat, cools cloud, reduces buoyancy

developing stage

unstable atmosphere

dry microburst

very dry topped by moist cooling beneath thunderstorm little or no rain virga in sky blowing dust rings

sound waves move faster in

warm air

dissipating

weakening updrafts and loss of the fuel source after 15-30 minutes

bergeron process

when air is in saturation with supercooled water, over saturated with ice, deposition of water vap over ice ice crystals grow rapidly at the expense of super cooled drops

vertical structure of supercell thunderstorm

winds push rain away and updraft is not weakened so storm can continue maturing and maintain its structure for hours

frost

~ similar to dew BUT saturation occurs below 0oC deposits white ice crystals known as hoar frost e.g. car windshield phase change from vapor directly to solid (deposition) diabatic process