Definition
A measure of the average kinetic energy of the molecules in a substance, expressed in degrees Fahrenheit (°F), Celsius (°C), or Kelvin (K). In aviation, temperature is one of the four primary variables (along with pressure, density, and humidity) used to describe the state of the atmosphere and to predict aircraft and engine performance.
Plain English
How hot or cold something is. In flying, it usually refers to how warm or cold the outside air is, because that affects how the airplane and engine perform.
Context Anchor
Seen in weather reports, preflight planning, performance charts, and cockpit temperature readings.
Derivation
From the Latin temperatura, meaning 'a proper mixing or proportion.' Originally it described the balance of hot and cold qualities in a substance. The modern meaning — a measurable degree of heat — kept the idea that temperature describes a condition or state, not a thing in itself.
Why Pilots Care
Temperature directly affects air density, engine performance, takeoff distance, and the risk of icing or overheating.
Grounding Statement
On a hot day, the same airport can feel normal to you but act like a higher airport to the airplane because the warmer air is thinner.
Intuition Check
Do not treat temperature as just a comfort number. In aviation, temperature helps determine how the air, engine, and airplane will behave.
Example Sentence 1
Before takeoff, the pilot checked the outside air temperature to calculate density altitude.
Example Sentence 2
Rising engine temperature during the climb led the pilot to adjust power settings.