thetangle: Calculates angle between organism and sun

In ilyamaclean/microctools: Various worker functions for microclimc package

Calculates angle between organism and sun

Description

Calculates angle between organism's longitudinal axis and the direction of the solar beam

Usage

thetangle(alt, azi, slope = 0, aspect = 180, plate = FALSE)

Arguments

alt	solar altitude (degrees) as returned by solalt()
azi	solar azimuth (degrees) as returned by solazi
slope	slope angle (degrees) of organism's longitudinal axis (see details)
aspect	aspect (degrees relative to north) of an organism's longitudinal axis (see details)
shape	logical indicating whether organism is flat (leaf) or not (see details)

Details

Slope and aspect values are relative to the horizontal and north respectively. E.g. an upright human has a slope of 90 degrees, whereas a caterpillar facing down-slope as the same slope and apsect as the underlying terrain. Shape must be specified, as for a flat plate, azi has no effect on the angle between the organism and sun when slope is 0, but for spheres and cylinders azi has no effect on the angle between organism and sun when slope is 90. 90 degrees for a human, 0 for an organism on a flat surface. The function thetangle is used in the calculation of view factors for direct beam radiation and absorbed radiation and if the orientation of the organism is unknown, absorbed radiation can be calculated by assuming no direction bias in orientation and deriving results numerically as in the example for Fprad().

Value

angle between organism and sun (degrees)

See Also

Fprad(), Radabs()

Examples

alt <- c(0:90) # solar altitude
# Angle for upright human
theta <- thetangle(alt, azi = 0, slope = 90, aspect = 0)
plot(theta ~ alt, type = "l")

ilyamaclean/microctools documentation built on Jan. 25, 2023, 5:29 a.m.