Draw wind barbs

Draw wind barbs on an existing plot. This (at the moment) requires that the plot aspect ratio be 1.

Usage

windBarbs(
  x,
  y,
  u,
  v,
  scale = 1,
  length = 0.5,
  step = 10,
  lwd = 1,
  col = 1,
  colFlags = 1,
  debug = 0
)

Arguments

x, y

numeric values indicating the locations at which to draw starting points of barbs.

u, v

numeric values indicating the velocity components in the x and y directions.

scale

numeric value indicating the length of barbs, as measured in the axis scale.

length

numeric value indicating the ratio of flag length to barb length.

step

numeric value indicating the step between speed categories. The default value of 10 is somewhat standard for speeds in knots.

lwd

line width of barbs.

col

colour of barbs.

colFlags

colour of interior of flags. This is 1 by default, to fill the flags with black ink, but lighter colours may be preferable to some eyes.

debug

integer that controls tell degree of debugging. If this is zero, work proceeds silently. Otherwise, some debugging information will be printed.

Author

Dan Kelley

Examples

library(atm)
L <- 8
plot(c(-L, L), c(-L, L), asp = 1, type = "n", xlab = "", ylab = "")
y <- -7
windBarbs(0, y, 70 * cospi(45 / 180), 70 * sinpi(45 / 180), scale = 2, colFlags = grey(0.9))
text(1, y, 70)
y <- y + 1
windBarbs(0, y, 70, 0, scale = 2, colFlags = grey(0.9))
text(1, y, 70)
y <- y + 1
for (i in 0:13) {
    windBarbs(0, y, 65 - 5 * i, 0, scale = 2, colFlags = grey(0.9))
    text(1, y, 65 - 5 * i)
    y <- y + 1
}