Temperature and Dew Point: Reading the Temp/Dew Point Group
Temperatura y punto de rocío: cómo leer el grupo de temperatura/punto de rocío
22°C
TEMP
12°C
DEW PT
Decode a temperature/dew point group, including negative values, and explain why a small spread between the two values signals a higher chance of fog or low clouds forming.
The gap between temperature and dew point is one of the most direct available clues to whether fog or low clouds are likely to form soon — a genuinely predictive piece of information hiding in what looks like just two plain numbers.
Teach It / Enséñalo
ENTIENDE
El GRUPO DE TEMPERATURA/PUNTO DE ROCÍO informa ambos valores, en grados Celsius enteros, separados por una barra diagonal: temperatura primero, luego punto de rocío. "22/12" significa una temperatura de 22°C y un punto de rocío de 12°C. El PUNTO DE ROCÍO es la temperatura a la que el aire necesitaría enfriarse para saturarse completamente de vapor de agua. Cuando un valor de temperatura o punto de rocío está por debajo de cero Celsius, una "M" (de "minus"/menos) antecede a ese valor específico en lugar de usar un signo de menos estándar — "M05" significa −5°C. La DIFERENCIA entre temperatura y punto de rocío es una señal de pronóstico genuinamente útil por sí sola: una diferencia pequeña significa que el aire está cerca de la saturación, haciendo más probable la niebla o nubes bajas.
¿Tiene sentido?
AVIATION WORDS · Palabras de aviación
DILO EN INGLÉS · SAY IT IN ENGLISH
“The temperature/dew point group gives you both values in Celsius, and the smaller the gap between them, the more likely fog or low clouds are to form.”
Ejemplo guiado
In the course's example METAR, "22/12" tells a pilot: temperature 22°C, dew point 12°C — a 10-degree spread, wide enough that fog or low clouds are not an especially high near-term concern under otherwise stable conditions, distinct from a report like "14/13" where a 1-degree spread would immediately raise that concern.
Real Aviation Application / Aplicación real en aviación
Checking the temperature/dew point spread — not just the two numbers separately — is a real, practiced habit among pilots and weather briefers specifically for anticipating fog and low-ceiling risk on a route or at a destination, beyond what the current METAR's cloud group alone already shows.
Ask Your Teacher / Pregúntale a tu maestro
- How exactly does dew point relate to relative humidity?
- Is there a specific spread number considered the real threshold for fog risk?
- Why does temperature/dew point use Celsius when many U.S. weather reports for the public use Fahrenheit?
HAMPTON'S .02 CENTS
The "M" prefix for negative values is a small detail but a common test trap — students who correctly understand dew point conceptually still sometimes misread "M05/M08" as "5 over 8" instead of "−5°C / −8°C" on a first pass, so it's worth a few quick negative-value-only decoding reps.
It Would Behoove You… Continue to the next lesson: the Altimeter group, the "A" in WWW VCT DAR.
Standards Alignment
CLASSROOM: METAR Fundamentals
FAA: FAA Aviation Weather Handbook (FAA-H-8083-28), Chapter 6
CERTIFICATION: Private Pilot, Part 107
SOURCES: Aviation Weather Handbook (FAA-H-8083-28)