26 lines
1.2 KiB
Go
26 lines
1.2 KiB
Go
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package internal
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import "math"
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const (
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refractionStandardPressureHPa = 1010.0
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refractionStandardTemperatureK = 283.15
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refractionAbsoluteZeroC = -273.15
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refractionLowerLimitAltitude = -5.0
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refractionUpperLimitAltitude = 90.0
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)
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// RefractionFromTrueAltitude 真高度到视高度的折射修正 / true-to-apparent altitude refraction.
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func RefractionFromTrueAltitude(trueAltitude, pressureHPa, temperatureC float64) float64 {
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if !validRefractionInputs(trueAltitude, pressureHPa, temperatureC) || trueAltitude <= refractionLowerLimitAltitude || trueAltitude >= refractionUpperLimitAltitude {
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return 0
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}
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angle := (trueAltitude + 10.3/(trueAltitude+5.11)) * math.Pi / 180
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scale := pressureHPa / refractionStandardPressureHPa * refractionStandardTemperatureK / (temperatureC - refractionAbsoluteZeroC)
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return scale * (1.02 / math.Tan(angle)) / 60
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}
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func validRefractionInputs(altitude, pressureHPa, temperatureC float64) bool {
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return !(math.IsNaN(altitude) || math.IsInf(altitude, 0) || math.IsNaN(pressureHPa) || math.IsInf(pressureHPa, 0) || pressureHPa <= 0 || math.IsNaN(temperatureC) || math.IsInf(temperatureC, 0) || temperatureC <= refractionAbsoluteZeroC)
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}
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