Transmittance due to rayleigh scattering — trans

Calculates transmittance due to Rayleigh scattering.

Usage

trans_rayleigh(...)

# Default S3 method
trans_rayleigh(datetime, lon, lat, elev, temp, ...)

# S3 method for class 'weather_station'
trans_rayleigh(weather_station, ...)

Arguments

...: Additional arguments.
datetime: POSIXlt object, date and time of the observation.
lon: Longitude in decimal degrees.
lat: Latitude in decimal degrees.
elev: Elevation above sea level in meters.
temp: Air temperature in °C.
weather_station: A weather_station object.

Value

Transmittance ratio from 0 to 1, unitless.

Details

The transmittance due to Rayleigh scattering is calculated using the formula: $$T_{rayleigh} = \exp(-0.0903 \cdot M_{abs}^{0.84} \cdot (1 + M_{abs} - M_{abs}^{1.01}))$$ where $M_{abs}$ is the absolute optical air mass. This is an Iqbal-style atmospheric transmittance approximation as presented in the Bendix (2004) appendix material cited for the package.

References

Bendix 2004, p. 245.

Examples

# Calculate transmittance due to rayleigh scattering
trans_rayleigh(
  datetime = as.POSIXlt("2023-08-06 12:00:00", tz = "UTC"),
  lon = 8.68, lat = 50.77, elev = 100, temp = 20
)
#> [1] 0.9080087