A wind barb plot displays wind speed and direction at specific locations using standard meteorological barb notation. Each barb consists of a staff pointing in the direction from which the wind blows, with short barbs (5 knots), long barbs (10 knots), and triangular pennants (50 knots) attached to indicate speed. This internationally recognized symbology enables rapid interpretation of wind patterns across weather maps and atmospheric data visualizations.
""" anyplot.ai
windbarb-basic: Wind Barb Plot for Meteorological Data
Library: letsplot 4.9.0 | Python 3.13.13
Quality: 87/100 | Updated: 2026-05-19
"""
import os
import numpy as np
import pandas as pd
from lets_plot import (
LetsPlot,
aes,
coord_fixed,
element_blank,
element_line,
element_rect,
element_text,
geom_point,
geom_polygon,
geom_segment,
ggplot,
ggsave,
ggsize,
labs,
scale_x_continuous,
scale_y_continuous,
theme,
theme_minimal,
)
LetsPlot.setup_html()
THEME = os.getenv("ANYPLOT_THEME", "light")
PAGE_BG = "#FAF8F1" if THEME == "light" else "#1A1A17"
INK = "#1A1A17" if THEME == "light" else "#F0EFE8"
INK_SOFT = "#4A4A44" if THEME == "light" else "#B8B7B0"
GRID_COLOR = "#CCCCCC" if THEME == "light" else "#3D3D3A"
BRAND = "#009E73"
np.random.seed(42)
# Generate grid of weather stations (8x6 grid = 48 stations)
n_x, n_y = 8, 6
x_coords = np.linspace(0, 140, n_x)
y_coords = np.linspace(0, 100, n_y)
X, Y = np.meshgrid(x_coords, y_coords)
x = X.flatten()
y = Y.flatten()
# Generate wind components (u = east-west, v = north-south) in knots
u = 15 * np.sin(x / 30) + np.random.normal(0, 3, len(x))
v = 10 * np.cos(y / 20) + np.random.normal(0, 3, len(y))
# Force calm winds at two stations (< 2.5 knots) for demonstration
calm_indices = [0, 5]
u[calm_indices] = 0.5
v[calm_indices] = 0.5
# Force high-speed winds at two stations (~54 knots) to demonstrate pennants
high_indices = [20, 21]
u[high_indices] = 45.0
v[high_indices] = 30.0
wind_speed = np.sqrt(u**2 + v**2)
# Wind barb geometry parameters
barb_length = 8
barb_spacing = 1.5
barb_tick_length = 2.5
# Build barb segments and pennant polygons for each station
segments = []
pennants = []
for i in range(len(x)):
speed = np.sqrt(u[i] ** 2 + v[i] ** 2)
angle = np.arctan2(-v[i], -u[i])
if speed < 2.5:
continue
cos_a, sin_a = np.cos(angle), np.sin(angle)
x_end = x[i] + barb_length * cos_a
y_end = y[i] + barb_length * sin_a
# Main staff
segments.append({"x": x[i], "y": y[i], "xend": x_end, "yend": y_end})
remaining_speed = speed
barb_position = barb_length - 0.5
perp_angle = angle + np.pi / 2
# Pennants: 50 knots each (filled triangles)
while remaining_speed >= 47.5:
bx = x[i] + barb_position * cos_a
by = y[i] + barb_position * sin_a
tip_x = bx + barb_tick_length * np.cos(perp_angle)
tip_y = by + barb_tick_length * np.sin(perp_angle)
base_x = x[i] + (barb_position - barb_spacing) * cos_a
base_y = y[i] + (barb_position - barb_spacing) * sin_a
pennants.append({"x": [bx, tip_x, base_x], "y": [by, tip_y, base_y]})
remaining_speed -= 50
barb_position -= barb_spacing
# Full barbs: 10 knots each
while remaining_speed >= 7.5:
bx = x[i] + barb_position * cos_a
by = y[i] + barb_position * sin_a
segments.append(
{
"x": bx,
"y": by,
"xend": bx + barb_tick_length * np.cos(perp_angle),
"yend": by + barb_tick_length * np.sin(perp_angle),
}
)
remaining_speed -= 10
barb_position -= barb_spacing
# Half barb: 5 knots
if remaining_speed >= 2.5:
bx = x[i] + barb_position * cos_a
by = y[i] + barb_position * sin_a
segments.append(
{
"x": bx,
"y": by,
"xend": bx + barb_tick_length * 0.5 * np.cos(perp_angle),
"yend": by + barb_tick_length * 0.5 * np.sin(perp_angle),
}
)
segment_df = pd.DataFrame(segments)
station_df = pd.DataFrame({"x": x, "y": y, "speed": wind_speed})
calm_df = station_df[station_df["speed"] < 2.5].copy()
anyplot_theme = theme(
plot_background=element_rect(fill=PAGE_BG, color=PAGE_BG),
panel_background=element_rect(fill=PAGE_BG),
panel_grid_major=element_line(color=GRID_COLOR, size=0.3),
panel_grid_minor=element_blank(),
axis_title=element_text(color=INK, size=20),
axis_text=element_text(color=INK_SOFT, size=16),
axis_line=element_line(color=INK_SOFT),
plot_title=element_text(color=INK, size=24),
)
plot = ggplot() + theme_minimal() + anyplot_theme
# Staffs and barb ticks
if len(segment_df) > 0:
plot = plot + geom_segment(aes(x="x", y="y", xend="xend", yend="yend"), data=segment_df, color=BRAND, size=1.2)
# Pennants as filled triangles
for pennant in pennants:
pennant_df = pd.DataFrame({"x": pennant["x"], "y": pennant["y"]})
plot = plot + geom_polygon(aes(x="x", y="y"), data=pennant_df, fill=BRAND, color=BRAND, size=0.5)
# Calm wind stations (open circles for speed < 2.5 knots)
if len(calm_df) > 0:
plot = plot + geom_point(aes(x="x", y="y"), data=calm_df, shape=1, size=6, color=BRAND, stroke=1.5)
# Station center dots
plot = plot + geom_point(aes(x="x", y="y"), data=station_df, size=2, color=BRAND)
plot = (
plot
+ labs(x="Longitude (°E)", y="Latitude (°N)", title="windbarb-basic · python · letsplot · anyplot.ai")
+ coord_fixed(ratio=1)
+ scale_x_continuous(expand=[0.1, 0])
+ scale_y_continuous(expand=[0.1, 0])
+ ggsize(1600, 900)
)
ggsave(plot, f"plot-{THEME}.png", path=".", scale=3)
ggsave(plot, f"plot-{THEME}.html", path=".")
Part of Wind Barb Plot for Meteorological Data on anyplot.ai.