Plain English Meaning
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.
Full 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.
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.