Instant Meteo Francia › Clouds & Nephology
The Cloud & Nephology Observatory details the vertical structure of the atmosphere above your municipality. Through vertical sounding profiles, WMO cloud classification, icing risk detection and nebulosity tracking across low, middle and high tropospheric decks, you can accurately anticipate sunshine, fog, ceiling height and aviation conditions over 48 hours.
The vertical sounding analyzes temperature, dew point and relative humidity from the ground up to 12,000 meters across standard pressure levels. It calculates the Lifting Condensation Level (LCL), cloud base altitude (ceiling), cloud top height and thermal inversions.
Nebulosity (sky fraction covered in percent and octas from 0/8 clear sky to 8/8 overcast) is broken down into the 10 WMO cloud genera across three altitude decks: low clouds below 2,000 m (stratus, stratocumulus, cumulus), middle clouds between 2,000 m and 6,000 m (altocumulus, altostratus, nimbostratus), high ice clouds above 6,000 m (cirrus, cirrocumulus, cirrostratus) and vertical convective towers (cumulonimbus).
By crossing sub-freezing temperatures (between 0 °C and -20 °C) with supercooled liquid water layers, the observatory identifies altitude bands prone to airframe icing for aviation and mountain activities, while distinguishing thin high cirrus from dense low stratus.
When cloud cover consists solely of high-altitude cirrus ice clouds above 6,000 meters, their low optical thickness lets most solar radiation through, unlike a thick layer of low stratus.
Icing occurs when relative humidity exceeds 85% in an atmospheric layer where temperature lies between 0 °C and -20 °C, indicating the presence of supercooled water droplets.
For optimal night-sky observation, look for time slots where all three cloud decks (low, middle and high nebulosity) simultaneously remain below 15% (0 to 1 octa).