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Weather n Climate E2
Weather n Climate -Exam 2 ch4-5
| Question | Answer |
|---|---|
| The process of [___1___] that occurs when water goes from the [___2___] phase to the [___3___] phase [___4___] energy, thereby [___5___] the atmosphere. | 1.)sublimation 2.)solid 3.)vapor 4.)consumes 5.)cooling |
| Mixing Ratio is a method of expressing water vapor content by using what unit of measurement | grams per kilogram |
| Wetbulb is a method of expressing water vapor content by using what unit of measurement | degrees |
| Relative Humidity is a method of expressing water vapor content by using what unit of measurement | percent |
| Saturation Mixing Ratio is a method of expressing water vapor content by using what unit of measurement | grams per kilogram |
| Dewpoint is a method of expressing water vapor content by using what unit of measurement | degrees |
| The process of [______] that occurs when water goes from the [_____] phase to the [_____] phase [______] energy thereby [_____] the atmopshere | The process of [deposition] that occurs when water goes from the [vapor] phase to the [solid] phase [releases] energy thereby [warming] the atmopshere |
| The temperature to which the air must cool in order for saturation to occur is called the: | dewpoint temperature |
| TRUE or FALSE The dewpoint temperature is always greater than or equal to the air temperature. | FALSE |
| As an air parcel [-----], its volume [-----], therefore its temperature [-----] due to [-----]. | As an air parcel [rises], its volume [increases], therefore its temperature [decreases] due to [expansion] |
| Rain shadows tend to form on the [-----] side of mountains, which are generally [-----] than the [-----] side of the mountain. | Rain shadows tend to form on the [leeward] side of mountains, which are generally [drier] than the [windward] side of the mountain. |
| According to the dry adiabatic lapse rate, for every 1000 meter increase in altitude (z), the temperature will: | decrease 10.0 C |
| what combination would result in the highest Lifted Condensation Level? | Temperature = 46 C Dewpoint = 19 C |
| The Hydrologic Cycle | -Annually 3.80 x 105 km3 of water evaporates/precipitates -Enough to cover the entire lobe with roughly 1 meter of rain -Six times more water is carried by the atmosphere over North America than by all the rivers on the continent |
| How much rain does Raleigh averagely get | Raleigh averages 42 in of rain a year. |
| Why is unique about Water(H2O)? | it is the only substance that can exists in all three phases (states) in the atmosphere |
| Solid (ice) | the molecules, lacking Kinetic Energy, are locked into a six-sided (hexagonal) crystal lattice, unable to move |
| Liquid (water) | the molecules, having more Kinetic Energy, are now able to slide by one another, but are still in constant contact. |
| Gas | the molecules now have enough Kinetic Energy to break all bonds and move about freely as ndividual molecules |
| Whenever water changes state, it either releases or consumes energy which is a process called | Latent Heat Transfer |
| Going from a high energy state to a low energy state ________ energy: | Release gas->->-Condensation->->-liquid->->-Freezing->->-solid gas->->->->Deposition->->->->solid |
| When you go from a high energy state to a low energy state releases energy the atmosphere is ______ | Warmed |
| Going from a low energy state to a high energy state ______ energy: | Consumes solid->->- Melting->->-liquid->->- Evaporation->->->gas solid->->->->Sublimation->->->->gas |
| When you go from a low energy state to a high energy state consumes energy the atmosphere is ____ | cooled |
| What are the four ways to express the water vapor content of the atmosphere, which as seen earlier comprises between 0.1 and 4% of its volume | -Mixing Ratio(MR) [g/kg] -Relative Humidity(RH) [%] -Dewpoint Temperature(Td)[F, C] -Wetbulb Temperature(Tw) [F, C] |
| The ratio of mass of water vapor in a unit mass of dry air, expressed as: | -grams of water vapor/1kg of dry air, g/kg, or g(kg^-1) -values range from: < 1 g/kg in polar regions > 20 g/kg in tropical regions |
| The amt. of water vapor necessary to saturate 1 kg of air is called the | Saturation Mixing Ratio |
| The amt. of water vapor necessary to saturate 1 kg of air is solely dependent upon the air’s temperature, therefore, | if you know the air’s T, you know its MRs. Rule of thumb: For every 10oC increase in T, the amount of water vapor needed to saturate the air (MRs) roughly doubles |
| Relative Humidity (RH) IS.. | The ratio of the air’s actual water-vapor content(MR) compared with the amount of water vapor required for saturation (MRs) which is depends on the T |
| The RH is the most familiar and widely used measure by the public, however its also the most misunderstood, because: | RH tells us how close the air is to being saturated, not how much water vapor is in the air! |
| When the RH reaches ______ the air is saturated | 100%,(i.e. when MR = MRs) |
| What are the two ways Relative Humidity Changes? | 1.Adding or Subtracting Moisture 2.Changes with Temperature |
| Adding or Subtracting Moisture | At constant T, the RH will increase if water vapor is added, until it reaches 100%: The addition of more water vapor will result in condensation, as the RH cannot (normally) exceed 100% |
| Changes with Temperature | Even if the water vapor content remains constant The RH will increase if the T decreases If additional cooling takes place after saturation is achieved, condensation & dew, fog and cloud development.. The RH will decrease if the T increase |
| What are the 3 Natural Changes in Relative Humidity | 1)Diurnal changes --->important in dew, frost and some fog formation 2)Advection--->important in some fog formation 3)Convection--->important in cloud formation, precipitation formation |
| What is it called when: -Early AM: T is usually lowest, RH is usually highest -Late PM: T is usually highest, RH is usually lowest | diurnal variations in RH are generally controlled by diurnal variations of the air Temperature |
| Dewpoint Temperature (Td)is... | The temperature to which the air must cool in order to become saturated |
| Dewpoint Temperature (Td)is | -point at which dew (frost) will form -RH=100% |
| The air’s dewpoint temperature: Td | provides the value of MR |
| the air’s temperature: T | provides the value of MRs |
| Td is generally | - Higher in the summer (50 – 70 F) compared to winter (0 - 30 F) - Higher near sources of water |
| Why is Td a useful indicator | Because the Td tells us exactly how much water vapor is in the air |
| Highest dew points will occur around ____ bodies of water | warm |
| The human body is less efficient at cooling itself when the RH is high, because | evaporation of perspiration (which as seen earlier, is a cooling process) is reduced. |
| Heat Index | -was developed by the NWS to draw attention to the dangers associated with high heat combined with high humidity. |
| Heat Index combines Temperature and Relative Humidity data to arrive at an: | Apparent Temperature |
| more people die because of ______in an average year than any other meteorological phenomenon | Heat Waves |
| Hygrometers | instruments that provide a measure of RH |
| Psychrometer | consists of two liquid-in-glass thermometers. The bulb of one is surrounding by a cotton wick that is saturated with water (wet bulb). |
| Air is then moved over the psychrometer allowing for evaporative cooling of the wet bulb thermometer which provides the: | WetBulb Temperature (TW) |
| WetBulb Temperature (TW) | The amount of cooling is proportional the amount of evaporation: -The drier the air, the more cooling takes place: the lower the Tw -more moist the air, the less cooling takes place: the higher the Tw |
| If the air is _____, no evaporation takes place, therefore no cooling occurs and thus | saturated T = Tw |
| the difference between T and Tw which is called the: | Wet bulb depression |
| Hair Hygrometer | -uses human hair which expands and contracts with increasing/decreasing -must be calibrated often |
| Electric Hygrometer | contains an electrical conductor coated with a moisture absorbing chemical. Electrical current changes with changing RH -lightweight -used on radiosondes |
| Infrared Hygrometer: | measures the amount of infrared energy absorbed [and hence from Kirchhoff’s Law] emitted by water vapor -used on satellites |
| The ________(also called the Equation of State) tells us that there is an inverse relationship between the volume of an air parcel and its temperature. | Ideal Gas Law |
| when a parcel of air rises | Its volume increases, therefore, its temperature decreases due to expansion |
| when a parcel of air sinks | Its volume decreases, therefore, its temperature due increases to compression. |
| In the Dry Adiabatic Rate (DAR)what happens When an UNSATURATED (i.e. RH <100%) parcel of air rises: | it expands and cools (adiabatically) at a constant rate of: -10 *C per 1000 meters -If the same parcel were to sink it would compress & warm at the same rate |
| Lifted Condensation Level (LCL) | The height at which the cloud first forms after could formation b/c T cools down to the Td, saturation and subsequently condensation occurs (RH now 100%) |
| TRUE or FALSE The drier the air the higher it will rise | TRUE |
| in the Wet Adiabatic Rate (WAR)what happens when a(now SATURATED) parcel of air continues to rise: | it expands and cools at a (nearly) constant rate of: -5 *C per 1000 meters The rate of cooling is reduced because condensation releases latent heat energy |
| Orographic (topographic) Lifting | air ascends up the windward side of mountains |
| Frontal Wedging | air masses often collide, forcing ascension |
| Convergence | -due to low pressure at the surface -due to sea-breezes |
| Localized Convective Lift | buoyant parcels of air rise due to unequal heating of the surface creating thermals |
| if a Parcel is forced to rise on the ______Side of the mountain, so the parcel expands and cools at the DAR. | Windward |
| LCL Equation | LCL = 125(30oC - 22oC)=1000 m |
| The parcel then sinks on the ______ Side of the mountain, so it compresses and warms at the DAR (evaporating the cloud), until it reaches the valley floor | Leeward |
| The now saturated (and likely precipitating) parcel continues to _____another 2000 m, but now cools at the WAR, until it reaches the top of the mountain | rise |
| The Leeward Side of the mountain which is much warmer and drier than it was on the other side of the mountain, allows for the formation of a | Rain Shadow |
| The Leeward side of mountains are generally ____ and _____ than the Windward side | drier and often warmer |
| TRUE OR FALSE moist air is actually less dense (~2%) than dry air | FALSE so the baseball announcers are incorrect - a baseball will travel ~ 2% farther in humid conditions |
| During clear, calm nights | -The ground cools very rapidly thru radiational cooling -The air that comes in contact with the ground cools thru conduction |
| If the T cools down to Td (i.e. RH = 100%), occurs | saturation |
| Dew Formation occurs | If the T (which equals Td)) are > 32oF |
| The water vapor molecules will condense into liquid water forming visible droplets on objects (i.e. grass, car) called dew. | Dew Formation |
| (White) Frost Formation occurs | If the T (which equals Td)) are < 32oF |
| The water vapor molecules deposit directly into frost | (White) Frost Formation |
| what kind of Nights favor dew/frost formation are those that experience “maximum radiational cooling” | -Clear skies -Calm Winds -Long nights |
| TRUE or FALSE dew and frost “fall” from the sky | FALSE they are formed insitu (in place) |
| Clouds: | visible aggregate (collection) of liquid water droplets and/or ice crystals suspended in the atmosphere |
| when an air parcel rises, it cools adiabatically and if the parcel’s T cools down to the Td, saturation and subsequently condensation occurs and______ | a cloud is formed, beginning at LCL |
| as dew/frost needs a surface to form on (i.e. grass), there must be a surface upon which water vapor can condense (deposit) in the air: | Cloud Condensation Nuclei (CCN) |
| As the water vapor molecules cool, they | -lose energy -move more slowly Picture the water vapor molecules “getting tired” and needing a place to rest. |
| Because CCN are so small and light | they can remain suspended for weeks |
| Even “clean” air contains over: | 1,000 CNN/cm3 |
| They enter the atmosphere through a variety of pathways, both | Natural: dust, salt spray, volcanic ash, fires, pollen Anthropogenic: sulfates, nitrates form fossil fuel burning (acid rain), fugitive dust |
| Some CCN are: | hygroscopic (water seeking) hydrophobic (water repelling) |
| Cloud Classification Form: | 1.cirrus form-(Latin for wisp) 2.cumulus form-(Latin for heap) 3.stratus form-(Latin for layer) 4.nimbus form-(Latin for rain) |
| Cloud Classification Height: | High -(>6 km) Middle -(2 to 6 km) Low- (< 2 km) Vertical -(2 to >6km) |
| Combinations of these forms and height give us ______ cloud types | ten major |
| High Clouds (> 6 km) | thin (tens of meters thick) -comprised solely of ice Crystals -non-precipitating -form in slowly rising |
| Cirrus (Ci) | -most common high cloud -called “Mare’s Tails” |
| Cirrostratus (Cs) | -often produce Halo around sun or moon, which is due to the refraction of light by ice crystals -often precedes precipitation |
| Cirrocumulus (Cc) | -form in a more turbulent environment -“Mackerel Sky” |
| Middle Clouds (2 - 6 km) | -thicker (hundreds of meters thick) -comprised mostly of liquid droplets w/some ice crystals -also non-precipitating |
| Altocumulus (Ac) | -often occur in large patches -bases are darker |
| Altostratus (As) | -no definite configuration (formless) -sun/moon barely visible |
| Low Clouds (< 2 km) | -thick (thousands of meters thick) -comprised mostly of liquid droplets with some ice crystals -some types produce drizzle |
| Stratus (St) | -resembles a fog that doesn’t reach the surface -sun is not visible -can produce drizzle |
| Stratocumulus (Sc) | -appear in long parallel rows or patches -rarely precipitate -1 km thick |
| Nimbostratus (Ns) | -produces continuous, generally light precipitation -completely blocks out the sun/moon -2 to 4 km thick |
| Clouds with Vertical Development (2 km to > 6 km) | -very thick (tens of thousands of meters thick) -comprised of liquid droplets and ice crystals -associated with unstable air -some produce precipitation |
| Cumulus (Cu) | -1 to 5 km thick -mostly liquid water -resemble cotton balls -dark, flat bases (LCL) -“Fair weather” clouds |
| Cumulonimbus (Cb) | -5 to 20 km thick -thunderstorm cloud -very strong updrafts, downdrafts -produce intense rain -produce lightning and thunder, hail and tornadoes |
| Cloud Varieties | Lenticular (Lens) Clouds Mammatus (Mammary) Clouds Anthropogenic Clouds -Contrail Clouds |
| Lenticular (Lens) Clouds | lens shape cloud that forms over and to the leeward side of tall mountain ranges |
| Mammatus (Mammary) Clouds | form in severe thunderstorms |
| Contrail Clouds | cirrus-like clouds that often form on exhaust of high-flying jets |
| High Clouds (> 6 km) | Cirrus (Ci) Cirrostratus (Cs) Cirrocumulus |
| Middle Clouds (2 - 6 km) | Altocumulus (Ac) Altostratus (As) |
| Low Clouds (< 2 km) | Stratus (St) Stratocumulus (Sc) Nimbostratus (Ns) |
| Clouds with Vertical Development (2 km to > 6 km) | Cumulus (Cu) Cumulonimbus (Cb) |
| Fog | a cloud with its base at or near the surface that restricts the visibility to 1 km or less |
| Fog formed by cooling | Produced when cooling of the air reduces T(TEMP.) to Td(dew point), hence saturation and condensation occurs |
| Radiation Fog | occurs at NIGHT, OVER LAND: when radiational cooling reduces T to Td -Generally associated with high pressure -light winds \ Maximum radiational -clear skies / cooling -occurs more often in winter (long nights) |
| Advection Fog | -Occurs when warm, moist air is advected over cooler surface reducing T to Td -UNLIKE radiation fog, advection fog requires the MOVEMENT of air EX. -San Francisco's Golden Gate -Warm air is moving over snow cover |
| TRUE OR FALSE radiation fog is sometimes called Valley fog | TRUE |
| Steam Fog | -occurs when cold air moves over warm water -the air immediately over the water surface first arms and gathers water vapor through EVAPORATION -it the rises (b/c it's less dense) allowing T will cool to Td -occurs when pond/lakes in autumn and wint |
| Average ANNUAL frequency with heavy fog | Area Frequency main type PCS >40days Advection NEC >40days Advection AM >40days Radiation Ral. 23-30days Radiation PCS= Pacific Coast States NEC= New England Coast AM= Appalachian Mtns |
| GOES (Geostationary Operational Environment Satellite) | -orbit above the equator at 36,000 km at the same rate the earth rotates -remains stationary above a location -Allows for continuous observation above a location -Limited Resolution |
| POES (Polar Operational Environment Satellite) | -Orbits NORTH-SOUTH at < 1,000km passing over both poles allowing the earth to rotate beneath -Allows for complete coverage of earth TWICE PER DAY -Better Resolution |
| What do Weather Satellites Provide? | 1.Visible images 2.IR(infrared) images 3.Water Vapor Image->energy |
| TRUE OR FALSE Condensation alone produces precipitation | FALSE! the process of condensation is entirely too slow to produce precipitation alone. Even under the most "ideal" conditions it would take several days to produce a small rain droplet solely through condensation |
| A cloud droplet must increase its volume by ______ in order to grow to the size of a rain drop | 1 MILLION or (1x106) |
| What are the 2 processes the allow clouds to form and precipitate in less than an hour? | 1.Bergeron Process-Cold clouds 2.Coalescence Process-Warm clouds |
| 95% of snow comes from________ | Nimbostratus clouds |
| Most cold clouds (outside of Tropical Latitudes)form in areas of the _______ where temperatures are well below freezing | Troposphere |
| Despite the fact that clouds formed in the Troposphere where their temp. is well below freezing these clouds are _______ | mostly comprised of liquid droplets |
| Super Cooled Could Droplets | are droplets below the freezing point but are still liquid |
| In order for freezing to take place the water vapor molecules must _________ | come in contact with unique particles that have CRYSTAL LATTICE SHAPE |
| Unique particles that have a crystal lattice shape are called: | ice crystals or freezing nuclei |
| Ice crystals or Freezing nuclei act as a nuclei for the formation of ice crystals trough ______ | DISPOSITION |
| The need for a freezing nuclei to initiate freezing is similar to the need of CCN to initiate condensation BUT_____ | there are far fewer freezing nuclei than CCN (Cloud Condensation Nuclei) ***1:1,000,000 Ratio*** |
| So even in clod clouds, the number of liquid water cloud droplets greatly exceeds the # of ice crystals, as a result: | -millions of liquid droplets will surround each ice crystal |
| B/c of subtle differences in the saturation mixing ratio(MRs) over an ice surface compared to that of a liquid surface water vapor molecules will: | EVAPORATE away from the liquid droplets & DEPOSIT onto the ice crystals |
| What do we call the growth process in which ice crystals grow at the expense of liquid water droplets | The Bergeron Process after the Swedish meteorologist who discovered it |
| as the ice crystals grow larger they eventually fall where: | They either reach the ground intact as snow OR They melt & reach the surface as raindrops |
| In the collision-coalescence process the AVERAGE cloud droplet had a diameter of | 20µ (0.02mm) |
| TRUE OR FALSE the siszes of warm clouds vary considerably, due in part to the size and type (hydrophobic, hygroscopic) of their CCN | TRUE |
| As a result, the variably sized warm cloud drops have variable: | Fall (or Terminal) velocities |
| Fall (or Terminal) velocities | is the point at which air resistance= gravitational force; so that the acceleration=0; and the drop falls at a CONSTANT velocity |
| Large drops fall faster and "overtake" small drops where they: | collide and coalesce(combine) |
| After Coalescing, they are larger, fall faster, further increasing the # of collisions, until, after a MILLION OR SO COLLISIONS, they are big enough to fall to the ground as a_______ | Lens shaped rain drop |
| what are the 2 important factors to Collision Coalescence Process | 1.Cloud Thickness 2.Cloud Updraft strength |
| THICK CLOUDS with STRONG UPDRAFTS can produce ________ than THIN CLOUDS with WEAK UPDRAFTS | larger drops and more intense rain |
| A warm STRATUS CLOUD is typically: | 1.THIN(~1000m thick) and 2.Has WEAK updraft(<0.1 mls) |
| A stratus cloud droplet would spend ~______min in the cloud and at most grow to ~_________ | 10-15 MINUTES 500µ( the size of drizzle) |
| A warm CUMULUS CLOUD is typically: | 1.THICK(>5000meter) 2.STRONG updraft |
| A cumulus cloud droplet would spend ~______hours in the cloud and at most grow to ~_________ | 1-2 HOURS 5000µ(the size of a large raindrop) |
| _____is the driest state where _____is the wettest | Nevada/Louisiana |
| Most of the precipitation we get comes from________ | The gulf of Mexico |
| Raleigh Averages ____per year of rain fall | 42 inches per year |
| Most of the West Coast Variability is b/c | of the mountains |
| while falling, the raindrops/snowflakes are often altered by... | the Atmospheric conditions encountered beneath the cloud |
| the Atmospheric conditions encountered beneath the cloud can: | -change form (i.e. snow to rain) -evaporate resulting in a phenomenon called VIRGA (Latin for streak) |
| Rain originates from with either _______ or ________clouds | NIMBOstarus or cumulisNIMBUS clouds |
| Nimbostratus clouds produce STRATIOFORM rain, characterized by: | -Continuous(hours to days) -Light rates(0.1-0.2 inches per hour) -Often called "OVERRUNNING PRECIPITATION" |
| Cumulonimbus clouds produce CONVECTIVE rain, characterized by: | -Generally brief(minutes to hour) -Intense rates(1-2 inches per hour) |
| Snow Results if | the temperature remains near or below freezing between the cloud base and the surface |
| Characteristics of six-sided ice-crystals | -Small, dry, powdery snowflakes are associated with temp. <<32 -Large, wet, sticky snowflakes are associated with temp. near 32 |
| Raleigh averages ________of snow fall | 7 inches |
| Sleet VS Glaze | how thick it is will determine what it is (either sleet or glaze) |
| Sleet results, if while falling, the snow first encounters a Warm layer (T>32)in which melting occurs and then encounters a ________ | DEEP cold layer(T<32) |
| DEEP cold layer above the surface in which complete freezing recurs BEFORE the precipitation reaches the surface: | -Bounces upon contact with the ground -Usually a transition precipitation |
| GLAZE (Freezing Rain) results, if while falling, the snow first encounters a Warm layer (T>32)in which melting occurs and then encounters a ________ | SHALLOW cold layer(T<32) |
| SHALLOW cold layer above the surface in which complete freezing recurs AFTER the precipitation reaches the surface: | -Adheres to trees/power lines -Can cause extensive damage |
| TRUE OR FALSE B/c of the App.Mtns the Piedmont is more susceptible to freezing rain | TRUE |
| Standard Rain Gauge is | A Funnel shaped collector that has an opening 10x wider than tube to allow for greater precision |
| Standard Rain Gauge | -can measure to nearest 0.01 inches -Any amount less is called a TRACE -DISADVANTAGE: needs a person to record data |
| Tipping Bucket is | A thimble-sized bucket that fills and tips over for every 0.01" which creates an electrical signal that can be recorded |
| Tipping Bucket | -Can be used remotely(w/o a person) -DISADVANTAGE: under-captures heavy rates |
| Snow Gauge is | A Standard Rain Gauge that has been modified with wind screens to ensure accurate collection. the snow is then melted to get :LIQUID EQUIVALENT PRECIPITATION |
| Typical ratio of snow to rain is | 10"snow:1"rain if we had 10" of snow it would melt down to 1" of rain |
| What does RADAR stand for? | RAdio Detection And Ranging |
| Each RADAR unit consists of: | A transmitter AND a receiver |
| Transmitter: | emits powerful pulses of energy |
| Receiver: | The energy from a transmitter meets an object a small % of the energy is REFLECTED BACK to the Receiver that amplifies & shows the signal on a screen as an echo providing precipitation: -type -Intensity -Location -Cumulative Amoun |
Created by:
rmedina16