Observation of hydrometeors other than clouds

(Section 3.3.2)

These hydrometeors may occur in the form of particles suspended in the atmosphere (for example, fog), of precipitation (for example, rain, drizzle, snow and hail), of particles raised by the wind (for example, drifting or blowing snow and spray) or else in the form of deposits (for example, dew, hoar frost, rime and glaze). In the case of precipitation, mention should be made as to whether it is uniform (intermittent or continuous) or of the showery type. For special studies, samples of rainwater may be kept for analysis. Exceptionally big hailstones should be weighed and measured and, if possible, photographed whole and in cross-sections. Photographs of hydrometeors in the form of deposits of dew, hoar frost, rime, etc., may be of value. The thickness of layers of rime or glaze should be measured. When a spout is observed, the height, diameter, sense of rotation and path of the cloud funnel (tuba) should be noted. Photographs, time-lapse images or videos should be taken if possible. It is also important to obtain information about any damage done by these hydrometeors, including taking photographs.