Extreme Weather Exam 2

Terms	Definitions
cirrus cloud
cirrus cloud	a high cloud composed of ice crystals in the form of white, thin, featherlike clouds in patches, filaments, or narrow bands. found at around or above 23,000 ft.
cirrocumulus cloud
cirrocumulus cloud	a high cloud that appears as a white patch of clouds without shadows. it consists of very small elements in the form of grains or ripples. found at or above 23,000 ft.
cirrostratus cloud
cirrostratus cloud	high, thin, sheetlike clouds, composed of ice crystals. frequently cover the entire sky and often produce a halo. found around or above 23,000 ft.
altocumulus cloud
altocumulus cloud	a middle cloud, usually white or gray. often occurs in layers or patches with wavy, rounded masses or rolls. Generally found between 6,500 and 23,000 ft.
altostratus cloud	...
altostratus cloud	a middle cloud composed of gray or bluish sheets or layers of uniform appearance. in the thinner regions, the sun or moon usually appears to be dimly visible. found between 6,500 and 23,000 ft.
nimbostratus cloud
nimbostratus cloud	a dark, gray cloud characterized more or less than continuously falling precipitation. it is rarely associated with lightning, thunder, or hail. found below 6,500 ft.
stratocumulus cloud
stratocumulus cloud	a low cloud, predominantly stratiform, with low lumpy, rounded masses, often with blue sky between them. found below 6,500 ft.
stratus cloud
stratus cloud	a low, gray cloud layer with a rather uniform base whose precipitation is most commonly dizzle. flow below 6,500 ft.
cumulus cloud
cumulus cloud	a cloud in the form of individual, detached domes or towers that are usually dense and well defined. it has a flat base with a bulging upper part that often resembles cauliflower. generally found below 6,500 ft.
cumulus congestus	a cumulus cloud that has condensed into a single large cloud with the tops resembling cauliflowers. the precipitation that occurs is always showery. found below 6,500 ft.
cumulus congestus
cumulonimbus cloud
cumulonimbus cloud	an exceptionally dense and vertically developed cloud often with a top in the shape of an anvil. this cloud is frequently associated with heavy showers, lightning, thunder, and hail. aka a thunderstorm cloud. base is found around 6,500 ft and can extend to over 23,000 ft.
isotherms	lines on a temperature/geographical map that connects places
elevation	a control factor of temperature, which involves air temperature variations with height above sea level. areas higher up will tend to be colder than those close to sea level.
latitude	a control factor of temperature, which involves the amount of solar radiation received/absorbed by the surface of the earth. think isotherm map.
temperature variations with latitude	-there is higher temp variation between latitudes in winter than in summer [think siberia] -hottest temps do not occur in tropics, but subtropical africa [arid deserts=high pressure and dry air]
distribution of land and water	land and water have different heating and cooling properties, which cause temperature to vary depending on the location, for example near a body of water air temps will be less extreme than in the middle of a continent.
heating/cooling property of water vs land	solar radiation penetrates land very shallowly, allowing for more to be absorbed rapidly and it heating/cooling quicker. solar radiation penetrates deep into water. 1- ocean convection and currents disperse heat over a greater area than land. 2- part of the radiation used to heat water is transported upward with water evaporation.
annual range of temperature	the highest and lowest temperatures of a certain location in a year.
annual range of temperature with relation to altitude	a higher annual range of temperature is found in higher altitudes when compared to equator, because fluctuations in absorption of solar radiation near equator are small.
ocean currents along eastern margins of continents	warm ocean currents warm water from the equator towards the poles. ex- responsible for england's similar climate to washington dc, despite its much higher latitude.
ocean currents along western margins of continents	cold currents transport cold water from poles towards the equator. ex- responsible for san fransisco's mild climate during the summer (average temp 62 degrees)
sensible temperature	the body's perception of temperature
human perception of temperature on cold, clear nights	we perceive temperatures to be warmer than a thermometer would read, because we emit infrared radiation, which creates a thin layer of warn air molecules around us that shields us from cold. wind would blow away the warm molecules, exposing us to the cold.
wind chill index	the cooling effect of any combination of temperature and wind expressed by loss of body heat
human perception of temperature on rainy days	we perceive the temperature to be lower than it is because water on our skin conducts heat away from us quicker than air can.
human perception of temperature on humid days	we perceive the temperature to be warmer than it is because less evaporational cooling from the skin can be experienced.
relative humidity definition	the ratio of the amount of water vapor actually in the air and the maximum amount of water vapor required for saturation t that particular temperature.
relative humidity equation	RH = water vapor content/water vapor capacity x 100%
what happens to relative humidity when air temperature increases (and water vapor content stays the same)?	relative humidity drops, because the air's capacity to hold water increases with heat.
dew point	the temperature to which air would have to be cooled for saturation to occur (with not change of air pressure or moisture content)
dew pressure relationship to water vapor content	-high dew point = high water vapor content -low dew point = low water vapor content
air temperature, dew point, and relative humidity relationship	-when air temperature and dew point are very far apart, the relative humidity is low -when the air temperature and dew point are close together, the relative humidity is high -when the air temperature and dew point are equal, the environment is saturated
wet-bulb temperature	the lowest temperature that can be reached by evaporating water into air
wet-bulb temperature relationship with evaporation/cooling	on hot days, when wet-bulb temperature is low, more evaporation takes place on skin. as wet-bulb temperature approaches the air temperature, less evaporation occurs
heat stroke	occurs when the body temperature reaches or exceeds 106 degrees associated with the failure of circulatory function
heat index	an index that combines air temperature and relative humidity to determine apparent temperature- how it feels outside
heat wave	a period of abnormally hot weather accompanied by high humidity
world's deadliest heat wave	August 2003 with between 35,000 and 52,000 heat related deaths
psychrometer	used to measure dew point and relative humidity consists of 2 thermometers, one wet one dry. the wet measure how much water evaporates in the air, which measures how dry the air is.
dew	water that has condensed onto objects near the ground when their temperatures have fallen below the dew point temperature. (the land emits infrared radiation and warms surrounding air to the point where water vapor turns to liquid).
frost	occurs when the air temperature is so low that water vapor in the air depositions, or freezes without condensing first.
many severe or extreme weather events occur with.....	convections, or rapidly rising air currents
when air is in stable equilibrium...	it will return to its original position after being lifted or lowered- it resists upwards or downward air movements
when air is in unstable equilibrium...	when given a little push, it will move further and further from its original position- it favors vertical air currents
parcel of air	an imaginary small body of air a few meters wide that is used to explain the behaviors of air
a rising parcel of air...	expands and cools
a sinking parcel of air...	sinks and warms
adiabetic process	a process that takes place without the transference of heat between a system (ex- parcel of air) and its surroundings.
dry adiabatic process (temperature)	as long as a parcel of air is unsaturated (RH < 100%), the rate of adiabatic process with constant at 10 degrees C per every 1 km change of elevation
moist adiabatic process (temperature)	the rate at which air temperature decreases with elevation when saturated (RH = 100%). it varies, but on average it is about 6 degrees C per 1 km.
air is stable when...	a parcel of air is colder than its surroundings, so it will be more dense and likely to sink back down to its original place.
air is unstable when...	a parcel of air is warmer than its surroundings, so it will be less dense and will continue to rise until it reaches the same temperature as the environment.
radiosone	a thermometer and hot air balloon that takes a vertical profile of temperature
environmental lapse rate	the rate at which the air temperature changes with elevation
absolutely stable atmosphere	an atmospheric condition that exists when the environmental lapse rate is less than the moist adiabatic rate. this results in a lifted parcel of air that being colder than the environment.
convection	vertical movement of air
advection	horizontal movement of air
absolutely stable air...	will resist vertical motion and will tend to move horizontally and thin (ie- cirrostratus, altostratus, nimbostratus, and stratus
atmosphere becomes more stable when lower air cools because of...	1) nighttime radiational cooling of the surface 2) an influz of cold surfaceair brought by the wind (cold advection) 3) air moving over a cold surface
atmosphere is most stable....	in the early morning. if surface air is saturated, radiational fog tends to form.
subsidence inversion	a temperature inversion produced by compressional warming -represents an absolutely stable environment
dry adiabatic process (dew point temperature)	as long as a parcel of air is unsaturated (RH < 100%), the rate of adiabatic process with constant at 2 degrees C per every 1 km change of elevation
moist adiabatic process (dew point temperature)	the rate at which air temperature decreases with elevation when saturated (RH = 100%). it varies, but on average it is about 6 degrees C per 1 km.
neutral stability	an atmospheric condition that exists in dry air when the environmental lapse rate equals the dry adiabatic rate. in saturated air, the environmental lapse rate is equal to the moist adiabatic rate.
absolutely unstable atmosphere	an atmospheric condition that exists when the environmental lapse rate is greater than the dry adiabatic rate. this results in a lifted parcel of air being warmer than air around it
conditionally unstable atmosphere	an atmospheric condition that exists when the environmental lapse rate is less than the dry adiabatic rate but greater than the moist adiabatic rate. stability of this system depends on whether the ricing parcel becomes saturated.
almost all thunderstorms form when the atmosphere is....	conditionally unstable.
condensation level	the level above the surface marking the base of a cumuli cloud- marking the point at which water vapor condenses into a cloud.
to form a cloud...	an unsaturated air parcel is somehow forced to rise, and it expands and cools at the adiabatic rate until its temperature cools to the dew point, where it is then saturated and condenses into a cloud.
the atmosphere becomes more unstable when...	the environmental lapse rate steepens, because of air aloft becoming colder or the surface air becomes warmer.
convective instability	the state of an unsaturated layer of air where the upper part is dry (cooling at the dry adaiabatic rate) and the lower point is moist (cooling at moist adiabatic rate) and the entire layer is lifted to the point where it becomes saturated and unstable. -this develops severe thunderstorms and tornadoes
these mechanisms are responsible for the development of the majority of the clouds we observe:	1) surface heating and free convection 2) uplift along topography 3) widespread ascent due to convergence of surface air 4) uplift along weather fronts
convection to create clouds	sun warms the earth, earth warms surface air, surface air rises and cools and condenses into a cumulus cloud. water vapor at the edges of clouds evaporate, releasing heat and begin to sink. also convection causes cooler air to sink back to the ground.
deep layers of conditional stability in atmosphere delegate what kind of cumulus cloud will form.	if stability starts close to the cloud base, a friendly cumulus cloud will form. if there is a deep layer of conditional instability, a cumulus congestus cloud will form. if an extremely deep layer of conditional instability exists, a cumulonimbus will form and a thunderstorm will probably occur.
entrainment	the mixing of environmental air into a pre-existing air current or cloud so that the environmental mixes in. -vertical development of cloud is dependent on this
lake-effect snows	snow storms that form on the downwind side of lakes because the atmosphere destabilizes as cool air flows over relatively warm water. the surface air is warmed and becomes more unstable, sweeps up moisture and becomes saturated, rise and corms cumuli clouds that will cause lots of snow.
orographic uplift	the lifting of air over a topographic barrier (ie a mountain). often causes condensation on windward side of mountains and often dry air on the leeward side, when the atmosphere is conditionally unstable. when atmosphere is stable, creates lenticular (wavy) clouds.