Weather Glossary and Terminology

7/23/2019 Weather Glossary and Terminology

1/23

Weather Glossary and Terminology

Below is a list of weather terms that are described in weather reports, forecasts andreadings. This data is collected from: the National Oceanic and Atmospheric

Administration's (NOAA) National Weather er!ice" the #et O$ice in the %nited&ingdom" anadas Weather O$ice" and the Astralian *o!ernment Brea of#eteorolog+.

Acid rain

lod or rain droplets containing polltants, sch as oides of slfr and nitrogen, toma-e them acidic (eg. p / 0.1).

Afternoon

Noon to snset.

Arctic air

A mass of !er+ cold, dr+ air that sall+ originates o!er the Arctic Ocean north ofanada and Alas-a.

Arctic high

A !er+ cold high pressre that originates o!er the Arctic Ocean.

Ball lightning

A relati!el+ rarel+ seen form of lightning, generall+ consisting of an orange orreddish ball of the order of a few cm to 23cm in diameter and of moderate lminosit+,which ma+ mo!e p to 4 m5s hori6ontall+ with a lifetime of a second or two.

Barber pole

A thnderstorm pdraft with a !isal appearance inclding clod striations that arecr!ed in a manner similar to the stripes of a barber pole. The strctre t+picall+ ismost prononced on the leading edge of the pdraft, while drier air from the rear7an- downdraft often erodes the clods on the trailing side of the pdraft.

BarometerAn instrment for measring atmospheric pressre.

Barometric pressure

The actal pressre !ale indicated b+ a pressre sensor.

Bitterly cold

8n winter, bitterl+ cold or !er+ cold, refers to more than se!en degrees elsis belownormal.


2/23

Black ice

Thin, new ice that forms on fresh water or dew co!ered srfaces" it is common onroadwa+s dring the fall and earl+ winter and appears 9blac-9 becase of itstransparenc+.

Blizzard8ncldes winter storm conditions of sstained winds or freent gsts of 20 mph ormore that case ma;or blowing and drifting of snow, redcing !isibilit+ to less thanone


3/23

Brisk

Wind in the range of 40 to 0 miles per hor when the temperatre is cold.

Broken clouds

lods which co!er between 05@ths and C5@ths of the s-+.

Calm

The absence of apparent motion in the air.

Celsius

A temperatre scale in which 6ero is the free6ing point of water and one hndred isthe boiling point.

Chinook

A hinoo- is a warm, dr+, gst+ wind that occasionall+ occrs to the leeward side of amontain range, particlarl+ the Doc-+ #ontains.

Cirrus cloud

igh clod, delicate, hair


4/23

Cold

8n the winter, cold refers to for to se!en degrees elsis below normal.

Cold Advection (CAA)

Transport of cold air into a region b+ hori6ontal winds.

Cold front

A narrow transition 6one separating ad!ancing colder air from retreating warmer air.The air behind a cold front is cooler and t+picall+ drier than the air it is replacing.

Cold low

A low pressre s+stem with cold air mass from near the srface to all !ertical le!els(also called a cold core low).

Cold-air-funnelA fnnel clod or (rarel+) a small, relati!el+ wea- tornado that can de!elop from asmall shower or thnderstorm when the air aloft is nsall+ cold (hence the name).The+ are mch less !iolent than other t+pes of tornadoes.

Collar cloud

Greentl+ sed as a s+non+m for wall clod, althogh it actall+ is a generall+circlar ring of clod srronding the pper portion of a wall clod.

Combined seas

The combined height of swell and wind wa!es.

ondensation

The process b+ which water !apor becomes a liid" the opposite of e!aporation,which is the con!ersion of liid to !apor. 8n Astralia, it is described as a changefrom a gas to a liid.

on7ence

A pattern of wind 7ow in which air 7ows inward toward an ais oriented parallel tothe general direction of 7ow. 8t is the opposite of di7ence. on7ence is not thesame as con!ergence. Winds often accelerate as the+ enter a con7ent 6one,

reslting in speed di!ergence which o$sets the (apparent) con!erging e$ect of thecon7ent 7ow.

ongests (or mls congests)

A large cmls clod with great !ertical de!elopment, sall+ with a cali7ower


5/23

An atmospheric condition that eists when the winds case a hori6ontal net in7ow ofair into a specied region. >i!ergence is the opposite, where winds case ahori6ontal net ot7ow of air from a specied region.

mlonimbs lod

A !erticall+ de!eloped clod, often capped b+ an an!il shaped clod. Also called athnderstorm clod, it is freentl+ accompanied b+ hea!+ showers, lightning,

thnder, and sometimes hail or gst+ winds. 8n Astralia, it is described as a hea!+,p$+, heaped, dar- clod of great !ertical depth, often bringing rain. ome ha!e adistincti!e an!il shaped head.

mls clod

A clod in the shape of indi!idal detached domes, with a 7at base and a blgingpper portion resembling cali7ower. 8n Astralia, it is described as a clod with awooll+, heaped appearance that often prodces rain.

mls congests

A large cmls clod with great !ertical de!elopment, sall+ with a cali7owera+ of the wee- (eg. #onda+)

#idnight to midnight.

>ebris clod

A rotating 9clod9 of dst or debris, near or on the grond, often appearing beneath acondensation fnnel and srronding the base of a tornado.

>ense fog

A fog in which the !isibilit+ is less than oneepression

A region of low atmospheric pressre that is sall+ accompanied b+ low clods andprecipitation.

>ew point

The temperatre to which the air mst be cooled for water !apor to condense andform fog or clods.

>iamond dst

A fall of noni7ence

A pattern of wind 7ow in which air mo!es otward (in a 9fan


6/23

>istrbance

A disrption of the atmosphere that sall+ refers to a low pressre area, cool air andinclement weather.

>ownbrst

A strong downdraft reslting in an otward brst of damaging winds on or near thegrond. >ownbrst winds can prodce damage similar to a strong tornado.

>owndraft

A colmn of generall+ cool air that rapidl+ sin-s to the grond, sall+ accompaniedb+ precipitation as in a shower or thnderstorm.

>ownslope wind

Air that descends an ele!ated plain and conseentl+ warms and dries. Occrs whenpre!ailing wind direction is from the same direction as the ele!ated terrain and oftenprodces fair weather conditions.

>raft

A draft is a small gst+ air crrent that mo!es pward or downward abrptl+" hence

the terms pdraft and downdraft.>rifting snow

%ne!en distribtion of snowfall cased b+ strong srface winds. >rifting snow doesnot redce !isibilit+. 8n anada, it is dened as snow blown to a height of less thantwo meters.

>ri66le

mall, slowl+ falling water droplets, with diameters between . and .0 millimeters. 8nAstralia, it is dened as fairl+ niform precipitation (rain) composed eclsi!el+ of!er+ small water droplets (less than 3.0 mm in diameter) !er+ close to one another.

>roght

Abnormall+ dr+ weather in a region o!er an etended period s$icient to case aserios h+drological (water c+cle) imbalance in the a$ected area. This can case schproblems as crop damage and waterr+

Gree from rain. Normall+ sed when preceding weather has also been relati!el+ dr+and dr+ weather is epected to contine for a da+ or so.

>st storm

An area where high srface winds ha!e pic-ed p loose dst, redcing !isibilit+ toless than one


7/23

nset to midnight.

=tended otloo-

A basic forecast of general weather conditions three to !e da+s in the ftre.

=tratropical c+clone

A storm that forms otside the tropics, sometimes as a tropical storm or hrricane

changes. ee table below for di$erences between etratropical and tropical c+clones.Top

Gahrenheit

The standard scale sed to measre temperatre in the %nited tates" in which thefree6ing point of water is 2 degrees and the boiling point is 4 degrees.

Gair

>escribes weather in which there is less than J543ths of opae clod co!er, noprecipitation, and there is no etreme !isibilit+, wind or temperatre conditions.

Gall wind

A strong, cold, downslope wind.

Gine

No rain or other precipitation (hail, snow etc.). The se of ne is generall+ a!oided inecessi!el+ clod+, wind+, fogg+ or dst+ conditions. 8n particlar note that nemeans the absence of rain or other precipitation sch as hail or snow < not 'good' or'pleasant' weather.

Glash 7ood

A 7ood that occrs within a few hors (sall+ less than si) of hea!+ or ecessi!erainfall, dam or le!ee failre or water released from an ice ;am.

Glood

A condition that occrs when water o!er7ows the natral or articial connes of astream or ri!er" the water also ma+ accmlate b+ drainage o!er low


8/23

Occrs when the srface air temperatre is epected to be 2 degrees Gahrenheit orbelow o!er a widespread area for a signicant period of time. 8n Astralia, the termEfree6eF is dened as the change from a liid to a solid.

Gree6ing

The change in a sbstance from a liid to a solid state.

Gree6ing dri66le

>ri66le that falls in liid form and then free6es pon impact with the grond or anitem with a temperatre of 2 degrees Gahrenheit or less, possibl+ prodcing a thincoating of ice. =!en in small amonts, free6ing dri66le ma+ case tra!eling problems.

Gree6ing fog

A sspension of nmeros minte ice cr+stals in the air, or water droplets attemperatres below 6ero degrees elsis, based at the =arth's srface, whichredces hori6ontal !isibilit+" also called ice fog.

Gree6ing le!el

The altitde in the atmosphere where the temperatre drops to 2G.

Gree6ing rainDain that free6es on ob;ects sch as trees, cars and roads, forming a coating or gla6eof ice. Temperatres at higher le!els are warm enogh for rain to form, bt srfacetemperatres are below 2 degrees Gahrenheit, casing the rain to free6e on impact.8n anada, free6ing rain is described to occr when the air temperatre is below 6eroelsis near the grond bt abo!e 6ero elsis higher p.

Gront

The bondar+ or transition 6one between two di$erent air masses. The basic frontalt+pes are cold fronts, warm fronts and occlded fronts.

Grost

The formation of thin ice cr+stals on the grond or other srfaces. Grost de!elopswhen the temperatre of the eposed srface falls below 2 degrees Gahrenheit andwater !apor is deposited as a solid.

Grost point

When the temperatre to which air mst be cooled to in order to be satrated isbelow free6ing.

G;ita scale

+stem de!eloped b+ >r Theodore G;ita to classif+ tornadoes based on winddamage. cale is from G3 for wea-est to G0 for strongest tornadoes.

G;iwhara e$ect

The G;iwhara e$ect describes the rotation of two storms arond each other.

Gnnel clod

A rotating, cone


9/23

A theor+ that increased concentrations of greenhose gases are casing an ele!ationin the =arth's srface temperatre.

*ood !isibilit+

#ore than 43 -ilometers.

*reenhose e$ect

The warming of the atmosphere b+ the trapping of longwa!e radiation (heat) beingradiated to space. The gases most responsible for this e$ect are water !apor andcarbon dioide.

*rond fog

hallow fog (less than twent+ feet deep) prodced o!er the land b+ the cooling of thelower atmosphere as it comes in contact with the grond. Also -nown as radiationfog.

*st

A brief sdden increase in wind speed. *enerall+ the dration is less than 3 secondsand the 7ctation greater than 43 miles per hor. 8n anada, gst is dened as a

sdden, brief increase in wind speed that generall+ lasts less than 3 seconds. 8nAstralia, gst is dened as an+ sdden increase of wind of short dration, sall+ afew seconds.

*stnado

*st front tornado. A small tornado, sall+ wea- and shortepending on the region of the %A, this generall+ means that for or more inches ofsnow has accmlated in 4 hors, or si or more inches of snow in J hors.


10/23

ea!+ snow warning

Older terminolog+ replaced b+ winter storm warning for hea!+ snow. 8ssed whense!en or more inches of snow or sleet is epected in the net J hors. A warning issed for winter weather conditions posing a threat to life and propert+.

ea!+ srf

the reslt of large wa!es brea-ing on or near the shore reslting from swells orprodced b+ a distant storm.

igh

An area of high pressre, sall+ accompanied b+ antic+clonic and otward wind7ow. Also -nown as an antic+clone. 8n anada, a high is described as an area of highatmospheric pressre with a closed, cloc-wise mo!ement of air.

igh clod

irrs, cirrostrats and cirrocmls.

igh ris- (of se!ere thnderstorm)

e!ere weather is epected to a$ect more than 43 percent of the area.

igh wind warning8ssed when sstained winds from J3 to C2 mph are epected for at least one hor"or an+ wind gsts are epected to reach 0@ miles per hor or more.

igh wind watch

8ssed when conditions are fa!orable for the de!elopment of high winds o!er all of orpart of the forecast area bt the occrrence is still ncertain. The criteria of a highwind watch are listed nder the high wind warning and shold inclde the areaa$ected, the reason for the watch and the potential impact of the winds.

ot or !er+ warm

8n smmer, hot or !er+ warm means more than se!en degrees elsis abo!e normal.

ot spot

T+picall+ large areas of pa!ement, these 9hot spots9 are heated mch ic-er b+ thesn than srronding grasses and forests. As a reslt, air rises pwards from therelati!el+ hot srface of the pa!ement, reaches its condensation le!el, condenses, andforms a clod abo!e the 9hot spot9.

midit+

The amont of water !apor in the atmosphere. 8n anada, it is described as theamont of moistre in the air.

rricane

A se!ere tropical c+clone with sstained winds o!er CJ miles per hor (1J -nots).Normall+ applied to sch storms in the Atlantic Basin and the Hacic Ocean east ofthe 8nternational >ate Line.

+grometer

An instrment sed to measre hmidit+.

Top

8ce cr+stals

8ce cr+stals are tin+ sprin-les that spar-le in the snshine li-e diamond dst andhang in the air.

8ce fog

A sspension of nmeros minte ice cr+stals in the air, or water droplets attemperatres below 6ero degrees elsis, based at the =arth's srface, whichredces hori6ontal !isibilit+. %sall+ occrs at


11/23

8ce pellets

Hrecipitation of transparent or translcent pellets of ice, which are rond orirreglar, rarel+ conical, and which ha!e a diameter of 3. inch (!e millimeters), orless. There are two main t+pes. ard grains of ice consisting of fro6en raindrops andpellets of snow encased in a thin la+er of ice.

8ce storm

Liid rain falling and free6ing on contact with cold ob;ects creating ice bild


12/23

Top

&atabatic

Wind blowing down an incline, sch as down a hillside" downslope wind.

&atafront

A front (sall+ a cold front) at which the warm air descents the frontal srface.

&illing frostGrost se!ere enogh to end the growing season. This sall+ occrs at temperatresbelow @ degrees Gahrenheit. 8n anada, a -illing frost is described as a frost se!ereenogh to destro+ annal plants and new growth on trees (in the spring) or to endthe growing season (in the fall).

&not

A measre of speed. 8t is one natical mile per hor (4.40 miles per hor). A naticalmile is one minte of one degree of latitde.

Top

La NiIa

A cooling of the eatorial waters in the Hacic Ocean.

Land bree6e

A wind that blows from the land towards a bod+ of water. Also -nown as an o$shorebree6e. 8t occrs when the land is cooler than the water.

Late

Grom snset (winter), from two hors before snset (smmer).

Leeward

itated awa+ from the wind" downwind < opposite of windward.

Left #o!er

A thnderstorm which mo!es to the left relati!e to the steering winds and to othernearb+ thnderstorms" often the northern part of a splitting storm.

Lifting

The forcing of air in a !ertical direction b+ an pslope in terrain or b+ the mo!ementof a denser air mass.

Lifting condensation le!el

The le!el in the atmosphere where a lifted air parcel reaches its satration point, andas a reslt, the water !apor within condenses into water droplets.

Lightning

An+ form of !isible electrical discharges prodced b+ thnderstorms.Li-el+

8n probabilit+ of precipitation statements, the ei!alent of a 13 or C3 percentchance.

Low

An area of low pressre, sall+ accompanied b+ c+clonic and inward wind 7ow. Also-nown as a c+clone.

Low clod

trats, stratocmls, cmls and cmlonimbs.

Low


13/23

#ainl+ clod+

#ore than half clod co!er bt with some brea-s in the clod. 8t can also bedescribed as clod+ with some snn+ periods.

#ainl+ snn+

#ainl+ snn+ means snn+ with some clod+ periods.

#ammats (or mamma clods)These clods appear as hanging, ronded protberances or poches on the nder

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Weather Glossary and Terminology