aviation weather unit

winds aloft

wind speed and direction at a certain altitude, also known as FB

low pressure area

causes air to rise, leading to bad weather and unstable air; rotate due to coriolis effect (counterclockwise in north; clockwise in south)

air mass

a large body of air with similar temperature and moisture properties, takes on characteristics of the region it forms

stationary front

frontal system where 2 masses meet but neither is strong enough to replace the other- causes dreary weather

instability

atmospheric condition where air rises easily, results in poor weather conditions such as storms and turbulence

convective activity

refers to development of cumulonimbus clouds and associated weather, including rain and thunderstorms

convective sigmet

“significant meteorological information” related to severe weather

embedded thunderstorm

thunderstorms occurring within a larger weather systems- are obscured and are difficult to detect

nexrad radar

“next generation weather radar”, provides information on precipitation and wind

satellite weather

used to observe and record changes in earth’s weather, broadcasted back to earth for more accurate forecasting information

severe turbulence

refers to unstable air encountered while in flight, can cause shaking of plane or significant drops/increases in altitude

primary gases that make up the atmosphere

nitrogen, oxygen, argon, carbon dioxide

what happens to the density of humid air

density decreases because it is made up of water vapor molecules, which have a lower mass than nitrogen and oxygen in dry air

layers of atmosphere

troposphere, tropopause, stratosphere, mesosphere, thermosphere, exosphere

role of heat exchange in weather

all weather is a result of heat exchange and the uneven heating of earth’s surface

gas that makes up most of the atmosphere

nitrogen

atmospheric gas that has the greatest effect on weather

water vapor- crucial in cloud formation, convection, and humidityand plays a significant role in the greenhouse effect.

where does most weather occur

troposphere

does air temperature increase of decrease with elevation

decreases until tropopause

atmospheric pressure

force of air on the earth, decreases at higher altitudes

is it better to fly in warmer or cooler conditions

cooler: less moisture in the air, less chance of convective activity, better lift because of denser air molecules

how does temperature affect the altimeter

low: altimeter reads too high (lower than you think); hot: altimeter reads too low (higher than you think)

what happens to air when it is heated

it rises and cools

what happens to low pressure air

converges and rises

convection

circulatory action of a fluid causes by uneven heating- leads to patterns of rising and sinking air

main reason for uneven heating of the earth

earth’s rotation and revolution around the sun: sun hits earth at different angles

why does a hot air balloon fly

air inside is heated- lower density, causing it to rise

direction of global circulation patterns

equator toward poles: east in north, west in south

coriolis effect

because of earth’s rotation, weather moves in a curved path rather than a straight line

how does wind flow

high pressure to low pressure

lines that signify atmospheric pressure

isobars

what do close isobar lines signify

pressure is changing quickly over a small area

3 forces that influence speed and direction of wind

coriolis effect, friction, pressure gradient force

what geographical feature increases turbulence

mountains/hills

why is temperature colder at higher elevations

pressure is lower, so air molecules spread out and temperature decreases

adiabatic lapse rate

rate at which temperature decreases as altitude increases

long frontal lines of thunderstorms

squall lines