create_irr_day_cycle: Estimate a full irradiance diurnal cycle
In USGS-R/mda.lakes: Tools for combining models, data, and processing for lakes

Estimate a full irradiance diurnal cycle

create_irr_day_cycle(
  lat,
  lon,
  dates = as.POSIXct("1990-01-01"),
  irr_mean = 1,
  by = "hour"
)

`lat`	Latitude in degrees
`lon`	Longitude in degrees
`dates`	A vector of dates to generate the diurnal cycles, will be extrapolated to hour, min, etc based on input to `by`
`irr_mean`	The mean daily irradiance to match in the diurnal cycle (arbitrary units), must be the same length as `dates`
`by`	Timestep to generate sequence of times, see seq.POSIXt for options