Principles of Flight and Atmospheric Physics Vocabulary

Vocabulary flashcards generated from lecture notes covering atmospheric physics, temperature scales, pressure types, gas laws, fluid dynamics, and flight principles.

Lighter-than-Air Aircraft

Aircraft, such as hot-air balloons, that rely on buoyancy and rise when their overall density is less than the surrounding air.

Heavier-than-Air Aircraft

Aircraft, such as airplanes and helicopters, that rely on four main forces: lift, weight, thrust, and drag.

Lift

The aerodynamic force acting upward on an aircraft.

Weight

The force acting downward on an aircraft due to gravity.

Thrust

The force that moves an aircraft forward.

Drag

The force that opposes the forward movement of an aircraft.

Atmosphere

The layer of gases surrounding Earth, composed at sea level of $78\%$ nitrogen, $21\%$ oxygen, less than $1\%$ argon, less than $1\%$ carbon dioxide, trace gases, water vapour, and particles.

Temperature

A measurement of the kinetic energy of molecules.

Celsius Scale

A temperature scale where water freezes at $0^\circ\text{C}$ and boils at $100^\circ\text{C}$.

Fahrenheit Scale

A temperature scale where water freezes at $32^\circ\text{F}$ and boils at $212^\circ\text{F}$.

Kelvin Scale

An absolute temperature scale where $0\,\text{K}$ represents absolute zero.

Rankine Scale

An absolute temperature scale based on Fahrenheit-sized degrees.

Absolute Zero

The lowest theoretical temperature, approximately $-273.15^\circ\text{C}$ or $0\,\text{K}$, at which molecular motion almost completely stops.

Troposphere

The lowest atmospheric layer, approximately $6\text{ to }20\,\text{km}$ thick, containing most of the atmosphere's mass, about $99\%$ of water vapour, and almost all weather.

Tropopause

The boundary between the troposphere and stratosphere that acts as an inversion layer where temperature stops decreasing.

Stratosphere

The atmospheric layer extending to approximately $50\,\text{km}$ that contains the ozone layer and where temperature increases with altitude in its upper portion.

Stratopause

The boundary between the stratosphere and mesosphere where temperature stops increasing.

Mesosphere

The atmospheric layer where temperature decreases with altitude down to approximately $-100^\circ\text{C}$ and where many incoming meteors are destroyed.

Thermosphere

The upper atmospheric layer with extremely low air density and temperatures reaching approximately $2,000^\circ\text{C}$, containing electrically charged particles used for radio-wave transmission.

Exosphere

The atmospheric layer beyond the thermosphere with extremely few molecules that gradually transitions into outer space.

Static Pressure

Pressure that is not associated with movement.

Dynamic Pressure

Pressure associated with moving forces or fluids.

Atmospheric Pressure

The force caused by the weight of the air surrounding Earth, which decreases as altitude increases.

Differential Pressure

Pressure measured between two points.

Absolute Pressure

Pressure measured relative to a perfect vacuum.

Gauge Pressure

Pressure measured relative to the surrounding atmospheric pressure.

Standard Sea-Level Pressure

Standard atmospheric pressure at sea level, equal to $29.92\,\text{"Hg}$, $101.325\,\text{kPa}$, or $14.7\,\text{psi}$.

Standard Atmosphere

An ICAO standard reference atmosphere with sea-level conditions of $29.92\,\text{"Hg}$, $15^\circ\text{C}$, and $32.174\,\text{ft/s}^2$ used to consistently evaluate aircraft performance.

Air Density

The amount of mass in a given volume of air, affected mainly by altitude, temperature, pressure, and humidity.

Density Altitude

Pressure altitude corrected for non-standard atmospheric conditions, where low air density reduces engine power and airframe aerodynamic efficiency.

Humidity

The amount of water vapour in the air.

Absolute Humidity

The actual amount of moisture present in the air.

Relative Humidity (RH)

The amount of moisture currently in the air compared with the maximum amount it could hold at that temperature, expressed as a percentage.

Dew Point

The temperature at which air becomes saturated ($100\%$ relative humidity) and condensation begins.

Boyle's Law

A gas law stating that pressure and volume are inversely proportional when temperature and mass remain constant ($P \uparrow \rightarrow V \downarrow$).

Charles' Law

A gas law stating that temperature and volume are directly proportional when pressure remains constant ($T \uparrow \rightarrow V \uparrow$).

Dalton's Law

Dalton's Law of Partial Pressures states that total pressure equals the sum of the partial pressures of the individual gases.

Torricelli's Law

A law describing the speed of fluid flowing out of an opening based on the height or depth of fluid above the opening.

Bernoulli's Principle

A principle stating that as the velocity of a fluid increases, its static pressure decreases.

Mass Flow Rate

The amount of air or mass passing a point per unit of time, which remains constant during steady flow in a duct.

Newton's First Law

The law of inertia stating that an object at rest stays at rest, and an object in motion stays in motion in a straight line unless acted upon by an outside force.

Newton's Second Law

The law of acceleration stating that the force required to change an object's motion depends on its mass and acceleration ($F = ma$).

Newton's Third Law

The law of action and reaction stating that for every action, there is an equal and opposite reaction.