public void CalculateBarometricPressureWithHumidity(double measuredValue, double temperature, double altitude, double relativeHumidity,
double expected)
{
var result = WeatherHelper.CalculateBarometricPressure(Pressure.FromHectopascal(measuredValue),
Temperature.FromCelsius(temperature), altitude, relativeHumidity);
Assert.Equal(expected, result.Hectopascal, 2);
}
public void ToStringDefault()
{
using (new SetCultureForTest("de-CH"))
{
Pressure p = Pressure.FromHectopascal(1024.24);
Assert.Equal("1024.24hPa", p.ToString());
}
}
/// <summary>
/// Calculates the barometric pressure from a raw reading, using the reduction formula from the german met service.
/// This is a more complex variant of <see cref="CalculateSeaLevelPressure"/>. It gives the value that a weather station gives
/// for a particular area and is also used in meteorological charts.
/// <example>
/// You are at 650m over sea and measure a pressure of 948.7 hPa and a temperature of 24.0°C. The met service will show that
/// you are within a high-pressure area of around 1020 hPa.
/// </example>
/// </summary>
/// <param name="measuredPressure">Measured pressure at the observation point</param>
/// <param name="measuredTemperature">Measured temperature at the observation point</param>
/// <param name="vaporPressure">Vapor pressure, meteorologic definition</param>
/// <param name="measurementAltitude">Height over sea level of the observation point (to be really precise, geopotential heights have
/// to be used above ~750m)</param>
/// <returns>The barometric pressure at the point of observation</returns>
/// <remarks>
/// From https://de.wikipedia.org/wiki/Barometrische_Höhenformel#Anwendungen
/// </remarks>
public static Pressure CalculateBarometricPressure(Pressure measuredPressure, Temperature measuredTemperature, Pressure vaporPressure,
double measurementAltitude)
{
double x = (9.80665 / (287.05 * ((measuredTemperature.Kelvin) + 0.12 * vaporPressure.Hectopascal +
(0.0065 * measurementAltitude) / 2))) * measurementAltitude;
double barometricPressure = measuredPressure.Hectopascal * Math.Exp(x);
return(Pressure.FromHectopascal(barometricPressure));
}
public void ConversionFactorTests()
{
Pressure p = Pressure.FromMillibar(1024.24);
Assert.Equal(p, Pressure.FromHectopascal(1024.24));
// Conversion factor from mmHg to Pascal
Assert.Equal((1.0 / 0.00750062) * p.MillimeterOfMercury, p.Pascal, 5);
// 1 inch = 25.4mm
Assert.Equal(p.MillimeterOfMercury / 25.4, p.InchOfMercury, 3);
}
public void Compare()
{
Pressure a = Pressure.FromHectopascal(950.21);
Pressure b = Pressure.FromHectopascal(920.59);
Pressure c = Pressure.FromPascal(95021);
Assert.NotEqual(a, b);
Assert.True(a != b);
Assert.True(a.CompareTo(b) > 0);
Assert.True(a == c);
Assert.True(b < a);
Assert.True(a > b);
Assert.True(a >= c);
Assert.True(a <= c);
Assert.False(a < b);
}
public void AltitudeIsCalculatedCorrectlyAtMslpAndDefaultTemp(double expected, double hpa)
{
var altitude = WeatherHelper.CalculateAltitude(Pressure.FromHectopascal(hpa));
Assert.Equal(expected, Math.Round(altitude, 2));
}
public void TemperatureIsCalculatedCorrectly(double expected, double pressure, double seaLevelPressure, double altitude)
{
var temperature = WeatherHelper.CalculateTemperature(Pressure.FromHectopascal(pressure), Pressure.FromHectopascal(seaLevelPressure), altitude);
Assert.Equal(expected, Math.Round(temperature.Celsius, 0));
}
public void PressureIsCalculatedCorrectly(double expected, double seaLevelPressure, double altitude, double celsius)
{
var pressure = WeatherHelper.CalculatePressure(Pressure.FromHectopascal(seaLevelPressure), altitude, Temperature.FromCelsius(celsius));
Assert.Equal(expected, Math.Round(pressure.Hectopascal, 2));
}
public void AltitudeIsCalculatedCorrectly(double expected, double hpa, double seaLevelHpa, double celsius)
{
var altitude = WeatherHelper.CalculateAltitude(Pressure.FromHectopascal(hpa), Pressure.FromHectopascal(seaLevelHpa), Temperature.FromCelsius(celsius));
Assert.Equal(expected, Math.Round(altitude, 2));
}
/// <summary>
/// Calculates the barometric pressure from a raw reading, using the reduction formula from the german met service.
/// This is a more complex variant of <see cref="CalculateSeaLevelPressure"/>. It gives the value that a weather station gives
/// for a particular area and is also used in meteorological charts.
/// <example>
/// You are at 650m over sea and measure a pressure of 948.7 hPa and a temperature of 24.0°C. The met service will show that
/// you are within a high-pressure area of around 1020 hPa.
/// </example>
/// </summary>
/// <param name="measuredPressure">Measured pressure at the observation point</param>
/// <param name="measuredTemperature">Measured temperature at the observation point</param>
/// <param name="measurementAltitude">Height over sea level of the observation point (to be really precise, geopotential heights have
/// to be used above ~750m)</param>
/// <returns>The barometric pressure at the point of observation</returns>
/// <remarks>
/// From https://de.wikipedia.org/wiki/Barometrische_Höhenformel#Anwendungen
/// </remarks>
public static Pressure CalculateBarometricPressure(Pressure measuredPressure, Temperature measuredTemperature,
double measurementAltitude)
{
double vaporPressure;
if (measuredTemperature.Celsius >= 9.1)
{
vaporPressure = 18.2194 * (1.0463 - Math.Exp((-0.0666) * measuredTemperature.Celsius));
}
else
{
vaporPressure = 5.6402 * (-0.0916 + Math.Exp((-0.06) * measuredTemperature.Celsius));
}
return(CalculateBarometricPressure(measuredPressure, measuredTemperature, Pressure.FromHectopascal(vaporPressure),
measurementAltitude));
}
/// <summary>
/// Calculates the actual vapor pressure.
/// </summary>
/// <param name="airTemperature">The dry air temperature</param>
/// <param name="relativeHumidity">The relative humidity (RH) expressed as a percentage</param>
/// <returns>The actual vapor pressure</returns>
public static Pressure CalculateActualVaporPressure(Temperature airTemperature, double relativeHumidity)
{
return(Pressure.FromHectopascal((relativeHumidity * CalculateSaturatedVaporPressureOverWater(airTemperature).Hectopascal) / 100));
}