Description Usage Arguments Value References
View source: R/radiation_functions.R
Calculates the beginning, midpoint, and end solar time angle (radians) for a given location and day of the year using Equations 29-33 from Allen et al. (1998). Used for calculations at an hourly or shorter timestep.
1 | hour_angle(tmid, tL, Lm, Lz)
|
tmid |
date and time of the midpoint of the time period POSIXct. |
tL |
length of the time period, from lubridate function "interval_len". |
Lm |
longitude of the measurement site (degrees west of Greenwich). |
Lz |
longitude of the center of the time zone used for measurements (degrees west of Greenwich). For example, Lz = 75, 90, 105 and 120° for the Eastern, Central, Rocky Mountain and Pacific time zones (United States) and Lz = 0° for Greenwich, 330° for Cairo (Egypt), and 255° for Bangkok (Thailand). |
omega1 |
solar time angle at the beginning of the period (radians) |
omega2 |
solar time angle at the end of the period (radians) |
Allen, R. G., Pereira, L. S., Raes, D., & Smith, M. (1998). Crop evapotranspiration: Guidelines for computing crop water requirements. Rome: FAO. Retrieved from http://www.fao.org/docrep/X0490E/x0490e00.htm.
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