VDI 3786 Blatt 9:2021-10

The current weather situation can be described by measuring its elements (e.g. temperature, humidity, radiation) and additionally by direct eye observation and assessment of the state of the atmosphere (e.g. snow showers, fog, thunderstorms). Eye observations of the immediate and recognizable effects of the current weather condition on the environment allow qualitative and quantitative statements to be made. The best example of this is wind: instead of the measurable variable "speed", "force" is used to visually estimate air movement. Eye observations can be helpful for questions of air pollution prevention if measurements are not available or only insufficiently available.