Question | Answer |
order of layers of air in atmosphere and their temp trends | troposphere, stratosphere, mesosphere, and thermosphere, exosphere: inversions are in S and TH |
height of tropopause | variable, tends to be lower over tropical regions and higher over arctic regions |
top three permanent gases in atmosphere | oxygen (78), nitrogen (21), and Argon (.93) |
top two variable gases in atmosphere | carbon dioxide and methane (also ozone, if you count it) |
greenhouse effect | heat from the sun is reflected back out to space and some of it gets trapped by GH gases, keeping heat in and causing earth to warm |
temperature conversions | c = 5/9(F-32), K = c+273.15 |
latent heat..when consumed and released | energy in form of heat, consumed(solid to liquid) or released (liquid to solid) by a phase change. |
how modes of heat transfer are relevent to atmospheric processes | radiation from sun(most important), convection drives weather, conduction only relevent in first few cm of surface where earth gives off heat |
advection v convection | advection is a horizontal transfer of air and convection is air circulating in a cell with heat rising and cool air falling |
where do sun and earth emission spectra peak in the electromagnetic spectrum | both in visible light, sun at one half micrometer and earth at 10 micrometers |
why is there less cooling on cloudy nights | because clouds tends to hold the heat from the day in like a lid on a jar |
diurnal (daily) temp cycle | driven by earth's rotation, energy gains from the sun and losses from earth's emission. loss exceeds gain by 4pm when max temp is reached. |
three processes where water absorbs energy | sublimation (ice to vapor), evaporation and melting |
factors that control both diurnal and annual temp cycles (they are the same) | latitude(intensity and number of hours of sun), surface type(vegies block heat, etc, elevation and aspect(angle sun's rays strike surfaces)(both higher elevation and aspect cause larger temp variations), large bodies of water(cause smaller ranges, less ex |
three processes by which water releases energy | condensation, freezing, and deposition (air to ice) |
relative humidity v dew point | RH - actual from molecules of vapor v the saturation vapor pressure..tells just how close air is to saturation. Dew point is the temp that air must be cooled to become saturated (without changed pressure) |
RH is temp independent and dew point is temp dependent. T or F | FALSE it's the other way around. |
saturation | occurs when the rate at which the number of molecules evaporating exactly equals the number condensing |
list the 5 types of fog | radiation, advection(mixing), evaporation(steam fog), upslope fog, valley fog |
radiation fog | when radiative cooling lowers temp in near surface air to dew point, forms at surface and thickens on up, happens on cool clear nights, heat rises from land cooling the bottom of air til it reaches saturation |
advection fog | warm moist air is cooled moving over a cool surface, ex is coasts |
evaporation fog | cold air mixes with warm wet air, mix is saturated, usually over warm water |
upslope fog | rising air parcel cools to condensation temp, reaching saturation |
valley fog | cool air drains inversion confines cool air below the dew point. cold air drainage reduces air temp to cond. point |
ten main cloud types | cirrus, cirrocumulus, cirrostratus, cumulonimbus(and mammatus), altocumulus, altostratus, nimbostratus, stratus, stratocumulus, cumulus |
characteristics of higher clouds and examples | icy, wispy, transmit light, less moisture..cirrus, cirrostratus, cirrocumulus |
characteristics of middle clouds | mostly water, some ice, usually water, even at freezing..altostratus, altocumulus |
cirrus | mare's tails, puffy streaks, wispy |
cirrostratus | halo around sun, doesn't look like cloud |
cirrocumulus | puffy, looks like sock fuzzies |
altostratus | darker cloud, spread out |
altocumulus | darker, obscures sun, puffy |
characteristics of low clouds | entirely water, (rarely ice, only in winter) |
stratocumulus | large puffy cottony, flat bottoms, sharp gradations in color and thickness |
nimbostratus | rain clouds |
stratus | layers, gradations in color |
storm sequence, cloud development | cumulus humilis to c. congestus to c nimbus |
mammatus | lobed at bottom, forms in sinking air assoc with sever tstorms..collapsing anvil clouds |
altocumulus castellanus (accas) | more vertical dev't than a normal antocumulus, can be precipitous (dries before it reaches ground) |
lenticularis | formed by upward deflection of air, often above topographic peaks, may be stacked (looks like dradle) |
pileus | like lenticularis, more subtle, forms above dev'g cumulus |
undulatus | wave-form, reflecting wave pattern in air flow, can be induced by topography, rippled |
kelvin-helmhotz | like crashing ocean waves in cross-section, results from shear |
the three extremely high clouds mentioned | nacreous, noctilucent, contrails |
nacreous | thin, form in stratosphere, low moisture, look ghostly, iridescent, all ice |
noctilucent | in mesosphere, low moisture and thin, bluish (hazy) |
contrails | made from jet engines of planes, hot exhaust is source of moisture |
cumulonimbus v nimbostratus | c.n. has vertical dev't and n.s. forms in sheets |
clouds form when air lifts and COOLS. T or F | True |
four processes of air lifting to form clouds | orographic, frontal, convection, and convergence of air at surface |
orographic lifting | creates precip on windward side and rainshadow (hot/dry) on leeward, ex is cascade range |
air is absolutely stable when environmental lapse rate is greater than adiabatic lapse rate | F. it's the opposite, think of an inversion |
convection lifting | air warms from sun and becomes buoyant and rises |
convergence of air at surface | low pressure systems or troughs, ex is stratus |
frontal lifting | warm air is stuck between two cells of cold air and is forced up |
saturated adiabatic lapse rate | cooling that occurs in a parcel of saturated air as it lifts, since it's wet it will also condense releasing latent heat |
environmental lapse rate | actual change in temp of air, depending on altitude |
dry adiabatic lapse rate | cooling of parcel of dry air as it rises |
warming occurs in a parcel of air as it rises. T or F | F. |
air cools because pressure decreases. t or f | T. |
air will fall back down when warmer than surroundings | F. will fall when cooler than surroundings |
if ELR is less than DALR, but ELR is greater than SALR, air is conditionally unstable | T. refer to diagram |
as air rises, it cools more quickly | F. air cools more slowly as it rises |
unstable air | is warmer than surrounds, so it rises |
stable air | lifted air is cooler than surroundings (and will sink), air dropped will be warmer than surroundings and rise |
absolutely unstable air | air lifted is warmer than surroundings, air cooled will be cooler than surroundings |
conditionally unstable air | air lifted at DALR is cooler than surrounding, once saturated cooling at SALR |
what is happening with the air with respect to moisture in it at the base of clouds | saturation occurs at lifting condensation level (LCL), this defines this place |
saturaded air is stable til it cross ELR and becomes warmer than surroundings. T or F | T |
if a stratus cloud breaks up, it cools. T or F | F, if it breaks up it will warm up |
what is the DALR | 10 degrees c per km |
describe conditonally stable air | DALR ) ELR ) MALR. Saturation occurs at LCL, that is the base of clouds. Unstable about the level of free convection, when it rises freely |
what are the conditions that favor stability | low ELR, cooling of low air, cold air advection, winds across cool surface or warming of high air |
what conditions favor instability | high ELR, warming of low air, solar heating of surface, warm air advection, wind across a warm surface or cooling of high air |
explains stability within a cloud | bottom is warmed by radiation from earth's surface, top is cooled by radiation upward, this causes increasing lapse rate, instability |
lifting air (which expands as it lifts, top more than bottom) will decrease the lapse rate in the sheet of air | F. it will increase the lapse rate |
why does lifting a sheet of air increase its lapse rase | because it expands as it lifts, top more than bottom, causing it to cool and inc lapse rate |
rain drop v cloud droplet | rain on avg is 2mm, cloud droplet is .02mm |
cirrocumulus are smaller than altocumulus | T |
drizzle, associated with stratus clouds, falls more slowly because of a large surface area and air resistance | F. surface area is smaller and resists air less |
how many cloud droplets make one raindrop | one million |
saturation pressure above ice is less than that above liquid water | True, because it's harder for water to come out fo ice into vapor phase, due to less moisture |
two ways to get precipitation | collision and coalescence AND bergeron-Wegener (ice crystal) process |
collision and coalescence | warm clouds, entirely above freezing, one drop is bigger with larger terminal velocity and starts to fall, colliding with others and they coalesce |
why are rain drop size limited | because once they reach terminal velocity, if they were to get any bigger they would split |
intensity of rain, scale | .01 to .1 in/hr is light.1 to .3 in/hr is moderatemore than.3 is heavy |
intensity of snow | based on visibility, more 1/2 mi is light1/4 to 1/2 is moderateless than 1/4 is heavy |
what controls shapes of ice | temperature and saturation |
freezing rain | supercooled, less than zero celcius, freezes to ice on surface (glaze), way worse than sleet |
sleet | clear ice pellets, less than 5 mm, formed by freezing of liquid drops |
hail formation | large balls of ice, forms in complex air motions of towering cumulonimbus cloud, bashing into supercooled water and growing concentric. Size depends on: how long in cloud, amount of water available for growth |
terminal velocity | larger mass to surface area ratio causes faster falling until it reaches t.v. and cannot speed up ..dec'n = acc'n |
ASOS | automated surface observing station. many instruments at various levels |
thermometer | measures temp, ASOS uses one to measure electrical resistance, as metal expands its ER increases |
sling psychrometer (hygrometer) | two thermometers slung through air with one wet sock and one dry. wet sock will cool and dry won't change if air is dry. If air is wet, wet bulb won't evaporate. amt of cooling is proportional to RH |
ASOS uses a dew point hygrometer. T or F | T |
aneroid barometer | uses volume of chamber, partial vacuum |
cup anemometer | measures wind, cups rotate in horizontal plane, gives speed |
aerovane | measures wind, propeller on wind vane determined velocity so both speed and direction are recorded |
tipping bucket | ASOS uses, measures rain, fill and tips, electronic signal produced, tips counted to get total (heated) |
weighing-type | measures all precipitation, accumulation gauge, newer at some ASOS |
water equivolence | measure of snow, ratio varies from 6:1 to 30:1 and depends on how packed snow is |
snow range sensor | measures snow, reflection from ground measumres distances, actual height, used in mountains |
snow pillow | measures snow, lands on pillow and is weighed, measures actual water equivolence |
celiometer | measures cloud height, cloud cover, has visibility sensor, uses scatter of light from clouds, precip ID sensor |
wind speed and temp are measured at 20 m in height. T or F? | F. They are measured at a height of 10m |
RADAR | radio detection and ranging, microwave transmitted in pulses, reflected by rain or snow, but not clouds, intensity of reflected energy corresponds to intensity of precip., not quite as accurate b/c it requires assumptions |
Doppler Radar | useful for detecting rotation in storms and tornadoes, measures wind speed where reg radar only gives reflection |
radiosonde and rawinsonde | instruments that measure temp, pressure and relative humidity, it adds wind speed and direction, balloons launched twice daily, product is a sounding on a skew-t diagram |
satellites | visible has best resolution, IR temp relates to cloud height, water vapor not clouds, all images come out black and white |
UTC | universal coordinated time (zulu) = greenwich mean time without DL savings. UTC -5=CDT in DL savings, UTC -6=CST off of DL savings |
wind | measured in mph or knots, direction described by azimuth |
knot | equal to one minute of latitude and 1 mile = 1.15 knots |
why doesn't air flow upward from high pressure to low pressure? | because the vertical gradient is countered by gravitational force-air tends to move due to temp and buoyancy |
surface winds blow parallel to H pressure to L pressure and upper winds blow obliquely across isobars. T or F | F. surface winds blow obliquely from H press to L press and upper winds blow parallel to isobards |
what controls the frictinal force | coriolis "force" - a product of other forces, |
how is pressure gradient force related to wind development | it is proportional to gradient and high gradient represents closely spaced isobars |
coriolis "force" | changes direction, but not speed of anything with respect to the ground, including air |
which ways are air deflected in each hemisphere b/c of the coriolis force | right in the N hemisphere, and left in the S hemisphere |
how are upper atmosphere winds measured | in iso-heights on surfaces of equal pressure |
process of how we get resultant winds in upper atmosphere | wind represents vector combination of PGF and Coriolis "force." Air moves form hi p to lo p due to PGF and is deflected by CF. Air is more deflected as CF increases with velocity. Winds end up parallel to isobars |
process of how we get resultant surface winds | frictional interaction with sea and land surfaces. friction slows wind, but doesn't reduce PGF, they are thirty degrees about isobars |
geostrophic wind | upper winds parallel to isobars, PGF and CF are equal and opposite |
IR cloud images | thin cirrus, bright and coldclear and dark |
visible cloud images | cumulonimbus and stratus (bright) |