The Wind KPI describes the distribution of wind direction and intensity in the site area, visualised as an interactive wind rose. The rose shows the frequency with which wind blows from each of the 16 compass points (N, NNE, NE, ENE, E, ESE, SE, SSE, S, SSW, SW, WSW, W, WNW, NW, NNW) and the breakdown by intensity class according to the Beaufort scale (0--12).
This is a visualisation-only KPI: no numerical quality score (A--E) is assigned. Instead, an interactive wind rose and monthly intensity line chart are produced, enabling assessment of site wind exposure across seasons. Wind conditions have direct ecological significance: they influence hive thermoregulation, plant evapotranspiration, pollen dispersal, and pollinator flight activity. Strong and frequent winds can significantly reduce nectar collection activity.
Wind data is generated on demand per site and year. Only complete years (from 2000 to the current year minus one) are supported.
Data come from the Open-Meteo Historical Weather Archive (ERA5 reanalysis), a globally consistent hourly dataset spanning 1940 to the present at approximately 10 km spatial resolution. Two variables are extracted: wind speed at 10 m (km/h) and wind direction at 10 m (degrees, 0° = North, clockwise).
Hourly observations are aggregated by calendar month. Continuous direction degrees are converted to 16 compass sectors of 22.5° each (North spans 348.75°--11.25°). Wind speed is converted to a Beaufort class (0--12) using the standard thresholds. The relative frequency is then calculated for each (direction, Beaufort class) pair, and the result is rendered as a polar wind rose.
The Beaufort scale maps wind speed to 13 intensity classes, each associated with observable physical effects:
| Class | Name | Speed (m/s) | Speed (km/h) | Description |
|---|---|---|---|---|
| 0 | Calm | 0.0 -- 0.3 | 0 -- 1 | Smoke rises vertically; sea like a mirror |
| 1 | Light air | 0.3 -- 1.6 | 1 -- 6 | Wind direction shown by smoke drift but not by vanes |
| 2 | Light breeze | 1.6 -- 3.4 | 6 -- 12 | Wind felt on face; leaves rustle; ordinary vanes moved |
| 3 | Gentle breeze | 3.4 -- 5.5 | 12 -- 20 | Leaves and small twigs in constant motion; wind extends a flag |
| 4 | Moderate breeze | 5.5 -- 8.0 | 20 -- 29 | Raises dust and loose paper; moves small branches |
| 5 | Fresh breeze | 8.0 -- 10.8 | 29 -- 39 | Small trees swaying; crested wavelets on inland waters |
| 6 | Strong breeze | 10.8 -- 13.9 | 39 -- 50 | Large branches in motion; telegraph wires whistling; umbrellas difficult |
| 7 | Near gale | 13.9 -- 17.2 | 50 -- 62 | Whole trees in motion; walking against wind difficult |
| 8 | Gale | 17.2 -- 20.8 | 62 -- 75 | Breaks twigs off trees; impedes walking |
| 9 | Strong gale | 20.8 -- 24.5 | 75 -- 89 | Slight structural damage (chimneys, slates removed) |
| 10 | Storm | 24.5 -- 28.5 | 89 -- 103 | Seldom inland; trees uprooted; considerable structural damage |
| 11 | Violent storm | 28.5 -- 32.7 | 103 -- 118 | Very rarely experienced; widespread damage |
| 12 | Hurricane | > 32.7 | > 118 | Devastation |
Unit: Relative frequency (%) per (direction, Beaufort class) pair. No single numeric score is produced.
Line Chart. A two-panel chart card combining a Wind Rose Radar Chart on the left and a Monthly Intensity Line Chart on the right, with summary badges at the top and a legend modal accessible via the info button.
Purpose: To answer the question "Where does the wind blow from, how often, and how strong?" -- enabling users to assess site wind exposure, identify prevailing directions, and understand seasonal intensity patterns.
Description: The chart card has a header row containing the title "Wind" (with a Topic E1 badge and an air icon), a weather-source label, a download button, and an info button that opens the Beaufort scale legend. Below the header, the left panel shows a month selector dropdown (Annual or individual months), a Dominant Direction badge, and an Average Beaufort badge above a circular wind rose. The right panel shows a monthly intensity line chart with a direction-specific title when a rose sector is selected. A "Remove selection" link appears when a direction is active.
How it's calculated: The wind rose shows the frequency percentage per compass direction across the selected time period (annual or a single month), with each of the 16 points colored according to the dominant Beaufort class for that direction. The monthly line chart shows the weighted average Beaufort value per calendar month, optionally filtered to a selected direction. Both panels draw from the same underlying data structure.
Note: The color scale is inverted -- calmer wind is green (good for ecological activity), stronger wind is red (disruptive).
Legend:
| Beaufort Range | Description | Color | Meaning |
|---|---|---|---|
| 0--2 | Calm to Light Breeze | ■ #00A67A | Best for ecological activity |
| 3--5 | Gentle to Fresh Breeze | ■ #FFD21E | Moderate wind exposure |
| 6--8 | Strong Breeze to Gale | ■ #FF8B16 | High wind stress |
| 9--10 | Strong Gale to Storm | ■ #FF5C5C | Severe wind stress |
| 11--12 | Violent Storm to Hurricane | ■ #FF367F | Extreme; devastating conditions |
The full 13-entry Beaufort legend (classes 0--12 with speed ranges in m/s) is shown in the legend modal opened via the info button.
Interpretation example:
If the wind rose shows a dominant NNW direction at 18% frequency with Beaufort 3 (green), the site experiences predominantly gentle north-northwest breezes -- a pattern favourable for pollinator flight and hive thermoregulation. If the monthly intensity chart shows Beaufort 5--6 (orange) in November--February and 2--3 (green) in June--August, the site has seasonal wind exposure that beekeepers should account for when positioning hives.
| Source | Provider | Coverage | Resolution | Period |
|---|---|---|---|---|
| Open-Meteo Historical Weather API (ERA5 reanalysis) | Open-Meteo / ECMWF | Global | ~10 km | 1940 -- present |
Hourly data are retrieved from the Open-Meteo Historical Weather Archive for the site polygon's centroid coordinates. Two variables are extracted: wind speed at 10 m above ground (km/h) and wind direction at 10 m (degrees, 0° = North, clockwise).
The processing pipeline applies the following steps:
The inverted five-level color scale maps Beaufort values to green (calm) through red (hurricane), applied over the 0--12 range to color each compass point on the wind rose.
Beaufort, F. (1806). "A Wind Force Scale." Originally developed for maritime use by the British Royal Navy. Adopted by the International Maritime Organization (IMO) and the World Meteorological Organization (WMO) as an international standard.
WMO (2008). "Guide to Meteorological Instruments and Methods of Observation" (CIMO Guide). WMO-No. 8. World Meteorological Organization, Geneva.
Hersbach, H., Bell, B., Berrisford, P., et al. (2020). "The ERA5 global reanalysis." Quarterly Journal of the Royal Meteorological Society, 146(730), 1999--2049. DOI: 10.1002/qj.3803
Open-Meteo (2023). "Open-Meteo Historical Weather API Documentation." https://open-meteo.com/en/docs/historical-weather-api