Definition
A recording instrument that continuously measures and traces temperature over time, typically using a temperature-sensitive element linked to a pen that draws a line on a rotating chart driven by a clockwork mechanism.
Plain English
A device that automatically draws a line showing how temperature changes over hours or days, so you can look back and see what the temperature was doing at any point.
Context Anchor
Seen in weather observing and airport weather station discussions, especially when reviewing how temperature has changed during a period of time.
Derivation
From Greek thermos (heat) and graph (to write). Literally 'heat writer' — an instrument that writes down the temperature.
Why Pilots Care
Temperature history matters when reviewing weather trends before a flight, checking storage conditions of temperature-sensitive cargo, or troubleshooting equipment that may have been exposed to extreme temperatures.
Grounding Statement
Picture a thermometer that keeps making its own temperature record as the day goes by.
Intuition Check
A thermograph is not just a temperature chart. It is the instrument or system that records the temperature changes.
Example Sentence 1
The mechanic checked the hangar's thermograph to confirm the avionics had not been exposed to freezing temperatures overnight.
Example Sentence 2
Forecasters compared the thermograph trace with the previous day's data to confirm the cold front had passed.