48 lines
1.2 KiB
Go
48 lines
1.2 KiB
Go
package weather
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import "math"
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// Attempts to complete missing fields that may not
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// be set by a specific provider, such as DewPoint and WindChill
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func (u *WeatherUpdate) Enrich() {
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if u.WindChillF == 0 {
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u.WindChillF = CalculateWindChill(u.TempOutdoorF, u.WindSpeedMPH)
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}
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if u.DewPointF == 0 {
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u.DewPointF = CalculateDewPoint(u.TempOutdoorF, float64(u.HumidityOudoor))
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}
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if u.BaromAbsoluteIn == 0 {
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u.BaromAbsoluteIn = u.BaromRelativeIn
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}
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}
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func CalculateDewPoint(tempF, humidity float64) float64 {
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// Convert temperature from Fahrenheit to Celsius
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tempC := (tempF - 32) * 5 / 9
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// Calculate the dew point using the Magnus-Tetens approximation
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a := float64(17.27)
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b := float64(237.7)
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alpha := (a*tempC)/(b+tempC) + math.Log(humidity/100)
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dewPointC := (b * alpha) / (a - alpha)
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// Convert dew point back to Fahrenheit
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dewPointF := (dewPointC * 9 / 5) + 32
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return dewPointF
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}
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func CalculateWindChill(tempF float64, windSpeedMPH float64) float64 {
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if windSpeedMPH <= 3 {
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// Wind chill calculation doesn't apply for very low wind speeds
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return tempF
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}
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// Formula for calculating wind chill
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return 35.74 + 0.6215*tempF -
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35.75*math.Pow(windSpeedMPH, 0.16) +
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0.4275*tempF*math.Pow(windSpeedMPH, 0.16)
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}
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