Capitulo 11 Weather Theory Part 3.pdf

8/12/2019 Capitulo 11 Weather Theory Part 3.pdf

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PrecipitationPrecipitation


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PrecipitationDepending on the form of precipitation, it

can reduce visibility, create icing situations,

and affect landing and takeoff performance

of an aircraft.

Precipitation in any form poses a threat to

safety of flight.

Often, precipitation is accompanied by low

ceilings and reduced visibility

Precipitation can create hazards on the

runway surface itself


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Icing


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Updrafts in a thunderstorm support abundant

liquid water with relatively large droplet sizes.

When carried above the freezing level, thewater becomes supercooled.

Supercooled water freezes on impact with an

aircraft.

The abundance of large, supercooled water

droplets makes clear icing very rapid between

0 C and 15 C and encounters can be

frequent in a cluster of cells.

Thunderstorms are not the only area where

pilots could encounter icing conditions. Pilots

should be alert for icing anytime the

temperature approaches 0 C and visible

moisture is present.


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Hail

Hail competes with turbulence as the greatest

thunderstorm hazard to aircraft.

Supercooled drops above the freezing level

begin to freeze.

Once a drop has frozen, other drops latch on

and freeze to it, so the hailstone grows

sometimes into a huge ice ball.

Large hail occurs with severe thunderstorms

with strong updrafts that have built to great

heights.


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Ceil ing and Visibil it y


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Ceiling

For aviation purposes, a ceiling is the lowest

layer of clouds reported as being broken or

overcast, or the vertical visibility into anobscuration like fog or haze.

Clouds are reported as broken when five-

eighths to seven-eighths of the sky is

covered with clouds.

Overcast means the entire sky is covered

with clouds. Los pilotos pueden acceder a dichainformacin a travs de los informes

meteorolgicos rutinarios de aeropuerto,

conocidos como METAR. En ellos, aparte de

la cobertura nubosa, se proporciona tambien

el llamado techo de nubes , que

definiramos como la altura a la que seencuentra la base de la capa inferior de las

nubes, por debajo de 20.000 ft (unos 6.000

metros) y que cubre ms de la mitad del

cielo.

Current ceiling information is reported by

the aviation routine weather report (METAR)


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Visibility

Visibility refers to the greatest horizontal

distance at which prominent objects can be

viewed with the naked eye.

Current visibility is also reported in METAR

and other aviation weather reports


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Fog is a cloud that begins withinFog is a cloud that begins within

50 feet of the surface.50 feet of the surface.

Fog

NieblaNiebla


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This type of fog occurs when the

ground cools rapidly due to

terrestrial radiation, and the

surrounding air temperature

reaches its dew point.


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Convective

Currents


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Inversin

LowLow--LevelLevel WindWind ShearShear


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TROPICALTROPICAL WEATHERWEATHER


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Technically, the Tropics lie between latitudes 23Technically, the Tropics lie between latitudes 23 N and 23.5N and 23.5 S. However, weatherS. However, weather

typical of this region sometimes extends as much as 45typical of this region sometimes extends as much as 45 from the Equator.from the Equator.

Estamos ante un clima clido, con una media de entre 25 y 27Estamos ante un clima clido, con una media de entre 25 y 27 CC..

La poca lluviosa tiene lugar cuando el sol est en el mismo hemisferio, muy alto en

el horizonte (en verano), mientras que la poca seca tiene lugar cuando el sol est

bajo en el horizonte (en invierno).

En este contexto el clima tropical seco y hmedo se caracteriza por tener dos

estaciones muy marcadas, una muy lluviosa y otra muy seca.


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Tropical waves, easterly waves, or tropical

easterly waves, also known as Africaneasterly waves in the Atlantic region, are a

type of atmospheric trough, an elongated

area of relatively low air pressure, oriented

north to south, which move from east to

west across the tropics causing areas of

cloudiness and thunderstorms.

Una onda tropical en el Ocano Atlntico "es

un tipo de vaguada", es decir, un rea

alargada de relativa baja presin orientada

de norte a sur.La ondas tropicales son transportadas hacia

el oeste por los vientos alisios, que soplan

paralelos a los trpicos, y pueden conducir a

la formacin de ciclones tropicales en las

cuencas del Ocano Atlntico norte y del

Pacfico nororiental

TropicalTropical WavesWaves Formacin de las ondas tropicalesFormacin de las ondas tropicales


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Weather over Open Sea

In the trade wind belt, skies over open

water are about one-half covered by clouds

on the average. Tops range from 3,000 to

8,000 feet depending on height of the

inversion. Showers, although more

common than under a subtropical high, are

still light with comparatively little rainfall.

Flying weather generally is quite good.

Island Weather

Mountainous islands have the most dramatic

effect on trade wind weather. Since trade

winds are consistently from approximately

the same direction, they always strike the

same side of the island; this side is the

windward side. The opposite side is the

leeward side. Winds blowing up the

windward side produce copious and frequent

rainfall.

Downslope winds on the leeward slopes drythe air leaving relatively clear skies and much

less rainfall.

The greatest flying hazard near these islands is obscured mountain tops.

Ceiling and visibility occasionally restrict VFR flight on the windward side in showers.

IFR weather is virtually nonexistent on leeward slopes.

If it becomes necessary toIf it becomes necessary to ditchditch in the ocean, look for a tall cumulus. If you see one,in the ocean, look for a tall cumulus. If you see one,

head for it. It probably marks a land surface, increasing your chances of survival.head for it. It probably marks a land surface, increasing your chances of survival.


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Capitulo 11 Weather Theory Part 3.pdf

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