Aviation Mid term

What is Air?

A mixture of several gases (composition depends on dry vs. humid conditions)

What is that percentages of nitrogen in completely dry air?

78%

What is the percentage of Oxygen in completely dry air?

21%

What makes up the remaining 1% of dry air?

Traces gases including Argon, Carbon Dioxide (CO2​), Neon, Helium, etc.

How does adding water vapor (humidity) affect the percentages of other gases in the air?

As water vapor (H2​O) increases, the percentages of all other gases decrease

What is the range of water vapor by volume in the atmosphere?

It varies widely, from trace amounts up to about 4%.

At what altitude is half of all atmospheric water vapor located?

Below 2 km (6,500 feet) altitude.

Water Vapor

clouds

clouds

potential impact on flight operations

Water Vapor

a vehicle for the transfer of heat energy and helps to regulate the
temperature of the Earth.

Why do you think the highest cumulonimbus clouds are found in the tropics and around the ITCZ? (two ingredients)

More heat, more water vapor

What is the Hydrologic (Water) Cycle?

The continuous circulation of water in Earth’s atmosphere.

What are the 5 most important processes in the water cycle?

• Evaporation

• Transpiration

• Condensation

• Precipitation

• Runoff

When is the water cycle considered balanced?

When the amount of water evaporating from Earth equals the amount falling back as precipitation.

Evaporation is when liquid becomes a vapor (gas). Primary source of evaporation on Earth comes from

The Ocean

Transpiration

is the evaporation of water from plants

Condensation

is the phase transition by which water vapor (gas) becomes a liquid

Precipitation

results when tiny
condensation particles grow in the
atmosphere through collision and
coalescence and then fall to the
Earth’s surface (they grow to be
too heavy)

all forms of precipitation is

Rain, sleet, snow and hail

Runoff

occurs when there is
excessive precipitation and the
ground becomes saturated
(cannot absorb anymore water)

Sublimation

phase transition from a solid to a
vapor (gas) without passing through the liquid
phase

Deposition

a stage in the water cycle when water
vapor turns into ice without becoming a liquid.

What are the three states of matter water can exist in?

Solid, liquid, and gas.

What makes water unique regarding its states of matter on Earth?

It is the only substance on Earth that exists naturally in all three states (solid, liquid, gas).

What naturally occurring substance has the highest specific heat capacity?

water

What does having a high specific heat capacity mean for water?

It has a much higher capacity for storing heat compared to other naturally occurring substances.

What is Sensible Heat?

Heat transfer that causes an object's temperature to change without changing its phase (state)

What is Latent Heat?

Heat transfer that causes an object to change its phase (e.g., solid to liquid or liquid to gas) without changing temperature.

How do you tell the difference between Sensible Heat and Latent Heat?

• Sensible Heat: Temperature changes (no phase change).

• Latent Heat: Phase changes (no temperature change).

Which 3 phase transitions absorb heat energy (latent heat) from the environment?

1. Melting (Solid → Liquid)

2. Evaporation (Liquid → Gas)

3. Sublimation (Solid → Gas)

Which 3 phase transitions release heat energy into the environment?

• Freezing (Liquid → Solid)

• Condensation (Gas → Liquid)

• Deposition (Gas → Solid

Three of which are associated with the absorption of latent heat by water from the environment

melting, evaporation, sublimation

Three of which are are associated with the release of heat energy by water to the environment:

freezing, condensation, and deposition

What is Saturation Capacity?

The maximum possible quantity of water vapor that an air parcel can hold at any given temperature and pressure.

What is the difference between Saturated and Unsaturated air?

• The air parcel is full (holding its maximum capacity of water vapor).

• The air parcel is not full (can still hold more water vapor).

what forms when saturation occurs and water vapor condenses?

Clouds, fog, dew

Relative humidity

Is a measure of how full the air is with water vapor, compared to the maximum amount it can hold at a
specific temperature.

warmer tempature

lower humidity

lower temparture

high humidity

dewpoint

Is a tempaturean air parel must be cooled to allow water vapor in the parcel to condenses into liquid water, like dew, fog or frost

low pressure causes

storms, snowers, clouds and rain and make people hurt due to it

high pressure leads to

clear skies, no weather but could turn into low pressure

Atmospheric Pressure

as you ascend the pressure decreases 1inhg per 1000ft

Atmospheric Pressure

Is the force per unit area exerted by the weight of the atmosphere

Barometer: contracts

high pressure

Barometer: Expands

Low pressure

when wafers get small its at

high pressure

when it expands its at

low pressure

station pressure

Measures at an airport, the actual pressure at field elevation.

mean sea level (MSI)

The most useful common reference to compare station pressure between station different altitudes

Density

A measure of how closely molecules are packed together. The closer togther they are greater the density.

High tempature

Lower density: warm air less dense and tends to rise

Lower tempature

Higher density: Colder air is desends and tends to sink

Heating air:

Molecules move faster and speared apart, causing the air expanded and bounce off each other.

Cooling air

Molecules slowed down and come together.

Density and volume

inverese molecules

large volumes (space) equals

small density

small volumes equals

large density

Density and Volume

related when the mass remains constant

Volume

increases with height because atmospheric pressure decreases

Increasing Volume

An air parcel expands (volume increases) without changing the amount of air

Decreasing Volume

If the air parcel is compressed (volume decreases) while keeping the mass the same

Air parcel with higher pressure is

Denser than an air parcel with lower pressure

When you go up up in the sky what happenes to the air pressure

it decreases

Is it better for aircraft to fly in cold or hot weather?

It is cold because it causes better lift for planes wing due to low density and molecules being slower and looser.

Density Altitude

pressure altitude corrected for temapture deviations from the standard atmospheric

what decreases aircraft performance

Higher density

what increases aircraft performance

Lower density

different ways high density is a hazard and reduces aircraft performance:

reduce power
reduce thrust

reduce lift

High Pressure :

Air is cooer and thus sinks down creating far weather

Low pressure:

Air is warmer and thus rises up creating clouds (unsettled weather)

A high pressure band is located??

near 30N at each pole

A low pressure band is located??

near 60N at each pole

what are Jet streams?

Narrow bands of strong wind in the upper levels of the atmosphere blowing west to the east.

Why do you think that the Jet streams moves from west to east?

The rotation of the eath moving from west to east.

What are the locations of Jet streams

Areas that have the greatest tempature changes with air rapidly sinking (high pressure) and rising (low tempature)

North winds come from

360 degrees

south winds come from

180 degrees

west winds come from

270 degrees

east winds come from

90 degrees

Forces that effect the wind is

• pressure gradient

• Coriolis Forces

• Friction

As air warms ascends it…

leads to low pressure at the surface

as air cools it descends it…

leads to high pressure at the surface

what is low pressure associated with

Bad weather (clouds, winds, precipitation, fronts)

what is high pressure associated with

Good weather (clear skies, light winds)

Pressure gradient force

A force that pushes air from high pressure to areas of low pressure

high pressure follows…

low pressure

Magnitude ofpressure gradinent force (left)

Isobars are widely, spaced apart, making the winds weak/light

Magnitude of pressure gradinent force (right)

Isobars are closely spaced, the pressure gradient force is strong and the winds are high/strong

Coriolis force

This force deflects air to the right in the Northern Hemisphere and to the left in the southern hemisphere.

if the wind increases what else increases?

coriolis friction

Friction

Slows diwn the wind, especially near the earth surface.

Local wind:

Area where cooler air will have high pressure and warmer air will have lower pressure.

Sea Breeze

Coastal local wind that blows from the sea to the land and is caused by tempatures differences when the sea surface is cooler than the land.

sea breeze directions at the surface:

From land to sea

sea breeze direction at altitude surafce

From land to sea

Land breeze

A coastal wind that blows from the land to the sea at night when the land’s temperatures is coler than the oceans

lake breeze

A shalllow ____ warms up rapidly and is less effective than a lake that is deeper