ATC Basics End of Course Review

BL

Blowing

DS

Duststorm

DZ

Drizzle

FG

FOG

FZ

Freezing

FC

Funnel Cloud

GR

Hail

HZ

Haze

IC

Ice crystals

PL

Ice pellets

DR

Low drifting

BR

Mist

PR

Partial

BC

Patches

RA (weather)

Rain

SA

Sand

SS

Sandstorm

MI

Shallow

SH

Showers

FU

Smoke

SN

Snow

SG

Snow grains

GS (weather)

Snow pellets

PY

Spray

SQ

Squall

TS

Thunderstorm

+FC

Tornado or waterspout

UP

Unknown Precipitation

VC

In the vicinity

VA

Volcanic ash

PO

Well developed dust/sand whirl

DU

Widespread dust

Where do virtually all aircraft fly?

The troposphere and the stratosphere

Troposhere

Lowest layer on Earth’s surface where almost all clouds and precipitation occurs, most weather takes place, air pressure and density decrease with altitude, temperature generally decreases with altitude

Tropopause

Transition boundary between the troposphere and the stratosphere

Stratosphere

Where the ozone layer and thunderstorm tops reside, temperature increases with altitude making it devoid of significant weather

Standard Atmosphere

Hypothetical vertical distribution of the atmospheric temperature, pressure, and density

Sea Level Pressure

29.92 inches mercury

Lapse rate

Decreases of temperature with height (2 degrees C/ 3.5 degrees F per 1000 ft)

Jet Streams

Migrating streams of high-speed winds present at high altitudes that typically flow west to east (sometimes north and south) and cause clean air turbulence

What are the two types of jet streams?

1) Polar, 2) Subtropical

Water Vapor

Gaseous form of water

Sublimation

Phase transition where solid is changed into gas without moving through the liquid stage

Evaporation

Phase transition where liquid is changed into gas

Temperature

Average kinetic energy of atoms within matter that directly impacts air’s capacity to hold water

True or False: Warm air can hold more water vapor than cold air

True

Dew Point

Temperature an air parcel must be cooled at to allow the water vapor in parcel to condense into water

What do higher dew points indicate?

Indicate higher quantities of water vapor

Condensation

Phase transition where gas is changed into a liquid

Relative Humidity

The ratio of water vapor actually in the air parcel compared to the amount of water vapor in the air could hold at a particular temperature

Saturation

Maximum possible quantity of water vapor that a parcel of air can hold at any given temperature and pressure

Saturated

Air parcel contains all the water vapor it can hold

Unsaturated

Air parcel has the capacity to hold more water vapor

Spread or Dew Point Depression

Difference between air parcel’s temperature and its dew point temperature

Cloud

Visible aggregate of minute water droplets and/or ice particles, formed when air is cooled to the dew point and becomes saturated

When does a cloud form?

A parcel of rising air expands and cools as pressure decreases with altitude and temperature/dew point spread decreases (going high, getting cool)

How does a cloud go away?

A parcel of sinking air warms as it encounters increasing pressure and is compressed and temperature/dew point spread increases

Cirriform

High-level clouds above 20000 ft usually composed of ice crystals that look thin and white but contains no significant icing

Cumuliform

White fluffy cotton balls that indicate upward vertical motion or thermal uplift of air that may produce icing, turbulence, etc (accumulate high)

Stratiform

Blanket or layer that often produces IFR weather but little to no turbulence of icing

Nimbo- or -nimbus

Raincloud

What are the two types of rainclouds?

1) nimbostratus, 2) cumulonimbus

A high

Occurs when there is a max of pressure and is known as an anti-cyclone where air flow diverges in a clockwise motion and sinks

What are the effects of a high?

Warm air sinks and compresses and holds more water vapor so clouds evaporate

A low

When there is a minimum of atmospheric pressure also known as a cyclone where air converges counterclockwise and risesW

What are the effects of a low?

Rising air expands and cools holding less water vapor so clouds and precipitation occur

Air Masses

Large body of air with uniform temperature and humidity and originate from an air mass source region

What are the 5 air masses?

1) Continental Arctic, 2) Continental Polar, 3) Continental Tropic, 4) Maritime Polar, 5) Maritime Tropical

cA

Cold, dry

cP

Cold, dry

cT

Hot, dry

mP

Cool, moist

mT

Warm, moist

What does a cold air mass moving a warm surface produce?

1) unstable air, 2) turbulence, 3) good visibility, 4) Cumuliform clouds and showers

What does a warm air mass moving over a cold surface produce?

1) stable air, 2) smooth air, 3) poor visibility, 4) Stratiform clouds, fog, drizzle

Front

Boundary or transition zone between 2 airmasses of different density and temperatures

Cold front

When colder air replaces warmer air that has a steep slope and air is forced upward causing a narrow band of cumulus clouds, showers, thunderstorms, unstable air, good visibility, and turbulence

Warm Front

When warmer air replaces colder air with a gentle slope so that air rising along the surface is gradual causing widespread stratiform clouds, stable precipitation, stable air, and poor visibility

Stationary front

Neither air mass is strong enough to replace the other so it remains stationary

Occluded

A composite of two front as a cold front overtakes a warm front or stationary front

What type of air mass produces stable air, smooth air, poor visibility, and stratiform clouds?

A warm air mass moving over a cold surface

Precipitation

Any form of water particles that fall from the atmosphere and reach the ground

What are the 3 ingredients necessary for precipitation?

1) Water vapor, 2) Lift, 3) Growth process

What are the primary sources of water vapor in the US?

1) Atlantic and Pacific Oceans, 2) Gulf of Mexico, 3) Great Lakes

When does SN occur?

When temperature is below freezing throughout the entire depth of the atmosphere

When does PL occur?

When precipitation passes through a shallow layer of warm air then a deep layer of below-freezing air that causes precipitation to refreeze

When does FRZA occur?

When precipitation passes through a deep warm layer of air then into a shallow cold layer of air not allowing it to complete refreeze before hitting the ground

How does RA occur?

When there is a deep warm layer of air based at the surface

NWS

Provides weather, hydrologic, and climate forecasts and warnings

What does the NWS produce?

1) Airmen’s Meteorological Information (AIRMETs), 2) Significant Meteorological Information (SIGMETs), 3) Convective SIGMETs, 4) Terminal Aerodrome Forecasts (TAFs)

CWSU

NWS offices located in every ARTCC providing meteorological consultation, forecasts, and advice to ARTCCs and other facilities with weather info that effects their missions, equipment, and staffing

CWC

Staffed by controllers and is the interface between CWSU meteorologists and ARTCC controllers and FAA facilities

Aviation Weather Hazard

Atmospheric condition that can cause damage to aircraft, personal injury, crash, or death

What is responsible for the most weather-related accidents?

Adverse wind

Crosswind

A wind not parallel to the runway or path of the aircraft

What could a crosswind do to an aircraft?

Drift off the side of the runway or side load on landing gear

Gust

A sudden, brief increase in the speed of wind

What does a gust cause?

It can cause the aircraft to bounce on the runway

Tailwind

Wind with a component of motion from behind the aircraft

What does a tailwind cause?

Longer takeoff roll, higher GS for landing and takeoff, small initial rate of climb