iind rose details and importance

8/11/2019 Iind Rose Details and Importance

1/30

How much force does the wind

exert?

Wind Force=wind pressure x area =v2 (ft/sec)x 0.0024 x area (ft2)

The wind produces how much force on an 8 x 6foot fence panel during a weak hurricane(60mph)? Force=0.0024 x (88ft/sec)2X 48ft2= 890 lbs

Katrina (130mph189ft/sec)=4110 lbs!

This principle affects everything frombuilding design to car fuel efficiency;aerodynamic lift in aircraft


2/30

Wind and Exposed Soil

Microscale winds bounce and skip sand grains, expose desertpavement, erode patterns into rocks, and shape sand duneswith ripples revealing wind direction.


3/30

Wind and Snow Surfaces

. Turbulent eddies of wind can trigger rolling of moist snow to

create cylindrical snow rollers.

Snow fences are used to accumulate snow so that it does notdrift over roads


4/30

Wind and Vegetation

Wind speeds increase with elevation above earth's frictional

surface, where stronger winds sculpt and denude the branchesof trees.Shelter belts may protect downwind property, but may alsocreate unwanted turbulent eddies.


5/30

Wind and Waves

-Water waves are generated by surface friction and eddies thatforce winds and water upward and downward.

-Wave height increases with wind speed, wind duration, andfetch (the length) of open water.


6/30

Wind Direction and Origin

-Wind direction is typically given as the origin from which it

blows, such as "westerlies" coming out of the west.-Counter-examples use the adverbs 'on' and 'up' to indicatedirection, such as 'onshore wind', and "upslope wind" for windmoving uphill.


7/30


8/30

Wind Rose Monthly or annual average speed and

directions represented graphically

d


9/30

Wind Measurements

-Pilot balloons observedwith theodolites, andrawinsondes are usefulways to detect winds in thelower atmosphere.

-Doppler radar detectschanges in wind speed.Also very helpful in

identifying developingstorms and tornadoes.


10/30

Thermal Wind Circulations

Th l Ci l i


11/30

Thermal Circulations

-Solar heating and radiational cooling of earth's surface generatescold-core thermal highs and warm-core thermal lows.-Winds can circulate between these two systems.


12/30

Thermal Winds

Changes in air temperaturecausing warm air to rise andcool air to sink can alsogenerate horizontal winds.

Rising warm air creates asurface low and upper levelhigh.

Sinking cool air creates asurface high and upper levellow.


13/30

Land/Sea Breeze Forms when large scale pressure

differences are small (large scale winds

are weak), or when large scale winds are

blowing in direction of breeze

development. There must be strong temperature

differences between land and water.

Leading edge of the sea breeze frontfrequently will cause lifting and trigger

thunderstorms.


14/30

Sea/Land Breezes

-Land heats more quickly than water, creating land-water

temperature differences along a coastline.

- During the day the land's warm-core thermal low draws a seabreeze, while at night, the warmer sea draws a land breeze.


15/30

Sea and Land Breezes

Opposing breezes

may converge onan isthmus of land,and this risingmoist unstable air

will triggerthunderstorms.

The leading edge ofland-water breezescan bring rapidchanges in humidityor pollutants.


16/30

Sea Breeze Animation

A i M


17/30

Asian MonsoonSeasonal reversal of monsoonwinds in southern Asia is

explained by continentaltemperature shifts.

Summer monsoon depressions of

low pressure and rains areenhanced by solar insolation,latent heat of condensation, andjet stream patterns.

El Nino-Southern Oscillation isalso known to affect monsoonintensity.


18/30

S th t US M


19/30

Southwest US Monsoon

Monsoon-like windsdevelop in July

across thesouthwestern U.S.region.

As the continentalinterior heats andrises, humid Gulfair sweeps increating instabilityand thunderstorms


20/30

-Solar heating of hill slopes creates airthat is warmer and lessdense than air at the same elevation over the valley, and

generates rising valley breezes.-Nighttime radiational cooling of the mountain slope createsrelatively denser air that sinks as a mountain breeze, or gravitywind.

Mountain and Valley Winds

M t i d V ll B


21/30

Mountain and Valley Breezes

Daily warming of mountain slopes that trigger valley breezesof moist air may result in cumulus clouds above mountainsummits.

K t b ti Wi d


22/30

Katabatic Wind

Elevated plateaus with snow covermay foster development of a

thin layer of high pressure cold air.

Pressure gradient winds are triggered due to lower pressure

above the adjacent valley, pushing cold air into the lower

valleycan be as strong as 100 kts

Common in Columbia River Gorge in Washington state; in the

former Yugoslavia, and France


23/30

Chinook Winds Known as the snow eater, or

Chinook winds Common in US Great Plains

Strong westerly winds force airupslope Moisture condenses and

precipitates when ascending

high mountains The air is then warmed upon

descent Air is much warmer and much

drier on the lee side of themountain

The drying/warming process happens any time the air rises and then descends overhigh mountain ranges, but Chinook winds form when upper level winds are strongand perpendicular to the mountain range

Chinook Wall Cloud


24/30

Chinook Wall Cloud

Chinook wall clouds are an indicator of the presence of

Chinook conditions.


25/30

ChinookRapid Temperature

Changes

Santa Ana Winds


26/30

Santa Ana Winds

Easterly winds that descend from southern California's elevateddesert plateau are heated by compression and lowered inhumidity.


27/30

Santa Ana Story Named after Southern California's Santa Ana

Canyon and a fixture of local legend andliterature, the Santa Ana is a blustery, dry andwarm (often hot) wind that blows out of thedesert.

In Raymond Chandler's storyRed Wind

, the titlebeing one of the offshore wind's manynicknames, the Santa Anas were introduced as"those hot dry [winds] that come down throughthe mountain passes and curl your hair and

make your nerves jump and your skin itch. On nights like that every party ends in a fight. Meek

little wives feel the edge of the carving knife and studytheir husbands' necks. Anything can happen."


28/30

Dust Devils


29/30

Dust Devils

-Not a tornado-On a hot, dry day the sun strongly heats the surface of theground, causing strong thermals.

Dust Devils


30/30

Dust Devils

-Winds near the surface cancause the thermal to spin

-The dust devil then creates a

rising column of dust and(light) debris.

iind rose details and importance

Documents