Aviation Meteorology Exam 2

What are the three types of clouds?

Cirriform, Cumuliform, Stratiform

Examples of high clouds?

Cirrus, Cirrocumulus, Cirrostratus

What are cirrus clouds?

White filaments of delicate ice crystals

What are Cirrocumulus clouds?

white sheet of ice crystals/ super-cooled droplets

What are Cirrostratus clouds?

White veil of ice crystals

Examples of middle clouds?

Altocumulus, Lenticular, Altostratus

What are Altocumulus clouds?

White/ gray cloud with rounded masses

What are Altostratus clouds?

Gray sheet of clouds often covering sky

What are Lenticular clouds?

White/ gray orographic clouds

Examples of low clouds?

Cumulus, towering cumulus, stratocumulus, stratus, nimbostratus, cumulonimbus

What are cumulus clouds?

Individual, dense, mass of white cloud with defined edges

What are towering cumulus clouds?

Cumulus cloud with vertical development

What are stratocumulus clouds?

Gray to white, rounded, flat-topped cloud

What are stratus clouds?

Gray sheet cloud with uniform base

What are nimbostratus clouds?

Dark gray sheet cloud with precipitation

What are cumulonimbus clouds?

Exceptionally dense and vertically developed white cloud

What is the warm process of precipitation process?

Collision- Coalescence- where droplets stick and form together and fall from the cloud

What is the cold process of precipitation process?

Bergeron- Findeisen- has ice crystals and super-cooled water droplets

How does rain fall?

Deep, warm layer keeps droplets above freezing after falling from the cloud

How does snow fall?

Occurs when temperature is below freezing through entire vertical column

How does freezing rain fall?

Occurs with a deep warm layer aloft and a shallow cold layer near the surface

How does sleet fall?

Occurs with a shallow warm layer aloft and a deeper cold layer near the surface

What is a continental Arctic (cA) airmass?

very cold, very dry (does not exist in summer)

What is a continental Polar (cP) airmass?

Cold, dry

What is a continental Tropical (cT) airmass?

Hot, dry (does not exist in winter)

What is a maritime Polar (mP) airmass?

Cool, moist

What is a maritime Tropical (mT) airmass?

Warm, moist (only airmass that can produce its own weather)

What is a cold front?

Cold air replacing warm air. Cumulonimbus clouds along front. Fast moving and clear skies behind

What is a warm front?

Warm air replaces cold air. Nimbostratus clouds along front with light and long-lasting precipitation. Slow moving front.

What is a stationary front?

Neither airmass moves. Precipitation is light, if any.

What is an occluded front?

Cold fronts lifts warm front. cP air on west on front, mP air on east side, mT air aloft. Heaving and long lasting precipitation.

What is a dryline?

Low-level boundary separating cT and mT air masses, most often over southern Plains. Occurs in spring and summer.

5 Steps to Cyclogenesis?

S1: Stationary front with cold air to north/ warm air to south

S2: Low pressure wave forms along front from opposing winds

S3: Wave cyclone intensifies and fronts become more pronounced

S4: Cold front overtakes slow-moving warm front and occlusion develops

S5: Occlusion increases and eventually cuts off supple of mT air at surface

What is convective turbulence?

Occurs from heating of Earth and the warm air rising and cooling to saturation. Top of clouds signifies the end of the convection. Pilots can just fly over clouds to avoid it, if possible. Cumuliform clouds can be signs of this turbulence.

What is mechanical turbulence?

Obstructions to the wind turns smooth wind flow into eddies. Mountains, buildings, trees are some examples. Leeward side of mountains can produce violent downdrafts. Lenticular clouds can be signs of this turbulence.

What is wind shear turbulence?

Associated with a wind shift or speed gradient at any level in the atmosphere.

What are the types of adverse winds?

Crosswinds, gusts, tailwinds, variable winds, wind shear

What is a crosswind?

Wind hat has a component directed perpendicularly to the heading of aircraft

What are wind gusts?

A fluctuation or wind speed with variations of at least 10 knots

What is a tailwind?

Wind with a component of motion from behind aircraft. Most dangerous adverse wind.

What are variable winds?

Winds that change direction frequently

What is wind shear?

Change in wind speed or direction, usually vertically

What is icing?

Any deposit of ice forming on an object. Occurs from super-cooled water droplets in clouds and is a major aviation hazard.

What are the 3 types of structural icing?

Rime, Clear (glaze), and mixed

What is rime icing?

Rough, milky, and opaque ice formed by instantaneous freezing of small, supercooled water droplets after they strike the aircraft. Most frequent type

What is clear icing?

Translucent ice formed by the relatively slow freezing of large, supercooled water droplets. More hazardous than rime icing

What is mixed icing?

Mix of clear and rime icing. Forms when aircraft moves through clouds with varying temperature, liquid content, and droplet size

What type of icing is found in stratiform clouds?

Rime or mixed icing. Layer between 3,000-4,000 ft. thick. Hazardous for being horizontally stretched out.

What type of icing is found in cumuliform clouds?

Clear or mixed icing. Smaller horizontally, but greater vertically. Intensity depends on cloud’s stage of vertical development

Air mass thunderstorm life cycle?

Towering cumulus stage: strong convective updrafts

Mature Stage: Precipitation descends to surface and drags adjacent air downward. Creates strong downdraft alongside the updraft

Dissipating Stage: Subsiding air replaces the updraft throughout clod. Moisture supply from surface is cut off

What are the ingredients needs for thunderstorm formation?

Sufficient water vapor, unstable air, and a lifting mechanism

What are the different types of thunderstorms?

Air mass, multicell, and supercell

What is a multicell thunderstorm?

A cluster of thunderstorms at various states of their life cycle. Can last several hours. New cells can form and more dangerous for aircraft than single cell thunderstorms.

What is a squall line?

Multicell thunderstorm that extends laterally for hundreds of miles.

What is a supercell thunderstorm?

Dangerous convective storm that consists of a single- quasi-steady rotation updraft that persists for an extended period of time. Dangerous updrafts and produce large hail and damaging winds.

What is radiation fog?

Most common in Kentucky. Produced over land when radiational cooling lower temps to dew point temp. Nighttime occurrence that dissipates when temps rise.

Formation Factors: clear skies with little to no surface winds, relatively moist surface layer, most common during fall

What is advection fog?

Forms when moist air moves over colder surface. Most common in coastal areas, but can occur over land. Thickens when winds increase up to 15 knots.

Formation Factors: Over cool bodies of water and carried inland by wind, more a hazard because it is thicker and can form anytime

What is upslope fog?

Forms when moist, stable air is adiabatically cooled to dew point temperature as it moves up sloping terrain. Winds of 5-15 knots are most favorable and can be quite dense and extend to high altitudes

What is frontal fog?

Type of upslope fog. Warm, moist air lifted over a front and occurs on north side of warm front

What is evaporation fog?

Occurs when very cold air moves across relatively warm water. Rising water vapor meets cold air and recondenses.

What is mist?

Visible aggregate of minute water droplets or ice crystals near the surface that reduces visibility to less than 7 miles but more than 5/8 mile

What is haze?

Suspension of extremely small particles invisible to the naked eye. Reduces visibility by scattering shorter wavelengths of light

What is smoke?

Suspension of small particles produced by combustion due to fires, industrial processes, or other sources

What is precipitation?

Any hydrometer than falls from cloud and reaches ground. Heavy snow can reduce visibility to zero. Rain can reduce visibility below 1 mile, except heavy showers

What is blwoing snow?

Strong winds can blow snow to reduce visibility to less than 7 miles. Dry, powdery snow is most hazardous

What is a dust storm/ sandstorm?

Strong winds blowing fine dust over an extensive area. Visibility can fall to near zero and damage intakes of engine and damage aircraft electronics

What is volcanic ash?

Fine particles of rock powder that originate from volcano. Can be detrimental to aircraft if flown through due to extensive damage to turbine blades and the engine.

What is the Intertropical Convergence Zone (ITCZ)?

Appears as constant bands of showers/ thunderstorms that encircle globe near or at equator.

What is the subtropical high?

West Coast of Continents: Air is more stable. Strong temperature inversions lead to fog and low stratus

East Coast of Continents: More unstable air. Moisture can penetrate the inversion leading to showers/ thunderstorms. Precipitation can be high

What are trade winds from sub-tropical highs to ICTZ?

Northeast Winds: north of equator

Southeast Winds: south of equator

What are offshore and onshore trade winds?

Offshore: skies clear and arid climate

Onshore: Abundant precipitation with numerous shower and thunderstorms

Trade winds on mountainous islands?

Windward side: Copious and frequent rainfall

Leeward side: Semiarid and mostly clear skies

What are monsoons?

Summer (wet): Draws warm, moist, and unstable air from oceans onto land

Winter (dry): Cold, dry, stable air moving offshore

What is a tropical wave (Easterly wave)?

Common disturbances that originate in the trade wind belt. Moves east to west along perimeter of sub-tropical highs

What are West African Disturbance Lines (WADL)?

Squall line that moves westward off African into Atlantic. Moves faster than Easterly waves. Some develop into tropical cyclones

What are the tropical cyclone stages?

Tropical wave/ WADL, Tropical Depression, Tropical Storm, Hurricane/ Cyclone

What are tropical cyclones?

Develop in warm water (over 80 degrees F) under low-level convergence and cyclonic wind shear with high pressure aloft. In tropics move east to west, in mid-latitudes moves west to east

Arctic Hazards

Fog and ice fog, blowing and drifting snow, Katabatic winds, and extremely cold temps