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BS EN IEC 60721-2-2:2024 - TC Tracked Changes. Classification of environmental conditions - Environmental conditions appearing in nature. Precipitation and wind, 2024
- A-30470146.pdf [Go to Page]
- undefined
- European foreword
- Endorsement notice [Go to Page]
- English [Go to Page]
- CONTENTS
- FOREWORD
- INTRODUCTION
- 1 Scope
- 2 Normative references
- 3 Terms and definitions
- 4 Rain [Go to Page]
- 4.1 General
- 4.2 Global distribution of rainfall
- Figures [Go to Page]
- Figure 1 – Average annual rainfall (AAR) for global land areas, based on 1961 to 1990 data [1]
- 4.3 Characteristics of rain [Go to Page]
- 4.3.1 Formation
- 4.3.2 Types of rain
- 4.3.3 Distribution of raindrop sizes
- 4.3.4 Terminal velocity
- Tables [Go to Page]
- Table 1 – Estimated number of raindrops per cubic metre for various rates of rainfall [1]
- 4.4 Rates of rainfall [Go to Page]
- 4.4.1 Instantaneous rates and clock-hour totals
- Table 2 – Terminal velocity of raindrops in still air [1] [Go to Page]
- 4.4.2 Frequency of instantaneous rates
- Figure 2 – Estimated conversion factor for converting to hours at instantaneous rate [1]
- Table 3 – Duration in the average year of instantaneous point rainfall equalling or exceeding specified rates [1]
- 4.5 Heavy rates of rainfall [Go to Page]
- 4.5.1 Thunderstorm rain
- 4.5.2 Prolonged heavy rain
- 4.5.3 Worldwide extremes
- Table 4 – Predicted worldwide extremes of rainfall [1]
- 4.6 Spatial variations of rainfall rate [Go to Page]
- 4.6.1 General
- Table 5 – Observed world maximum rates of rainfall [1] [Go to Page]
- 4.6.2 Rainfall rates below 2 mm/h
- 4.6.3 Rainfall rates between 2 mm/h and 10 mm/h
- 4.6.4 Rainfall rates between 10 mm/h and 25 mm/h
- Figure 3 – Average decay of correlation with distance, of 1 min rainfall rate and total storm rainfall rate [1] [Go to Page]
- 4.6.5 Rainfall rates exceeding 25 mm/h
- 4.7 Rainfall probabilities along a line
- Table 6 – Estimated duration (h) in the average year when stated distances along given tracks simultaneously have rainfall at or exceeding specific rates [1]
- 5 Snow [Go to Page]
- 5.1 General
- 5.2 Global distribution of the incidence of snowy weather
- Figure 4 – Estimated percentage of days on which an amount of snow equivalent to at least 1 mm of rainfall falls in northern and southern hemispheres [1]
- 5.3 Global distribution of the incidence and depth of lying snow
- 5.4 Mass, size, and fall-speed of snow
- Table 7 – Snow crystals: relation between mass (mg) and diameter (mm) of the sphere which just contains the crystal [1]
- Table 8 – Values of α and β for different crystal types [11]
- Figure 5 – Satellite derived average rainfall equivalent of lying snow and ice [1]
- 6 Hail [Go to Page]
- 6.1 General
- 6.2 Global distribution of hailstones
- 6.3 Seasonal variations in global distribution
- Figure 6 – Estimated average annual number of days per year withhail of diameter ≥ 15 mm [1]
- 6.4 Diurnal variation
- 6.5 Size of hail
- Figure 7 – Estimated average seasonal number of days per year with hail of diameter ≥ 15 mm, based on post-processed global model data (oceans excluded) [1]
- 6.6 Terminal velocity
- Table 9 – Number of hailstones per cubic metre (at about 4 000 m) for specified maximum hailstone size and specific ranges of stone size [1]
- 6.7 Duration and diameter of hail cell
- Figure 8 – Relationship between diameter and terminal velocity of spherical hailstones [1]
- 7 Ice [Go to Page]
- 7.1 General
- 7.2 Hoar frost
- 7.3 Rime ice (including in-cloud icing and freezing fog)
- 7.4 Glazed frost (including freezing rain and freezing drizzle)
- Figure 9 – Air temperature and wind speed criteria for the formation of different types of ice [1] [15]
- Table 10 – Meteorological parameters controlling atmospheric ice accretion [15]
- 7.5 Wet snow accretion
- 7.6 Water content of fog and cloud at temperatures below 0 °C
- 7.7 Altitude variations
- 8 Wind [Go to Page]
- 8.1 General
- 8.2 Mean wind speed [Go to Page]
- 8.2.1 General
- Figure 10 – Power spectrum of wind speed fluctuations [1] [Go to Page]
- 8.2.2 Variation of mean wind speed with height
- Figure 11 – Annual mean 10 m wind speed (m/s) for global land areas, averaged over the period 1961 to 1990 [1] [Go to Page]
- 8.2.3 Frequency of winds
- Figure 12 – Measurement stations with station numbers
- Table 11 – Details of stations, their location, elevation, observation rate and total number of observations [19]
- Table 12 – Percentile mean wind speed and percentage frequencies of measured wind speeds for each station [19] [20] [21]
- 8.3 Gustiness [Go to Page]
- 8.3.1 General
- 8.3.2 Gust factor
- 8.3.3 Gust ratios
- Table 13 – Terrain type and gust factor [1] [Go to Page]
- 8.3.4 Variation of gust speed with height
- Table 14 – Ratio of the probable maximum gust speed, averaged over time, to the mean hourly wind speed for level sites in open country [1]
- Table 15 – Suggested ratios for estimating maximum gust speed over short periods from a known mean hourly wind speed
- Table 16 – Factors for calculating maximum mean wind speed for various intervals using the mean speed measured over the hour [1]
- 8.4 Effects of topography
- 8.5 Wind types and extreme winds
- Table 17 – Spatial and temporal scales of meteorological wind systems plus characteristic wind speed ranges
- 8.6 Effects of wind
- Figure 13 – Vortex formation produced when wind strikes the corner of a structure
- Figure 14 – Contours of pressure coefficients produced by vortices
- 8.7 Wind in conjunction with other damaging agents
- Bibliography [Go to Page]
