5.3 Weather and Obstructions to Vision . The occurrence of weather and obstructions to vision is observed by nearly all stations. The definitions of the phenomena are given in FMH No. 1 and FMH No. 9. 5.3.1 Precipitation Measurements . At other stations, the observations may consist of the accumulation, rate of accumulation, time of occurrence, and duration. 5.4 Pressure .
Atmospheric pressure is measured and recorded in several different forms.
5.5 Temperature and Dew Point . The ambient air temperature is observed at most stations. These data are observed in accordance with FMH No. 1, FMH No. 9, and WSOH No. 5.6 Wind . At some stations, the maximum wind speed occurring during the day is recorded at stations having a continuous wind speed recorder.