Map Symbols Atlas

A visual legend: fronts, pressure systems, isobars, station plots, wind barbs, cloud cover.

Fronts

Colour = type. Symbol direction = direction the front is moving.

Symbol	Front	What to expect
	Cold front	Wind veer, temp drop, showers or squalls along front, clearing behind.
	Warm front	Gradual overcast, steady rain ahead, wind backs then steadies, warmer behind.
	Occluded front	Mix of both; typically near a mature low's centre. Cold air catching up with warm air.
	Stationary front	Weather parks overhead; can become a cyclogenesis zone.
	Trough / trof	Wind shift, pressure minimum, shower line possible. Not a true front.
	Squall line	Fast-moving line of thunderstorms. Gust front ahead of the visible rain.

L (red) / H (blue) mark low and high pressure centres. The number is central pressure in mb.

Isobars are drawn at 4 mb intervals (…1004, 1008, 1012…). Tighter spacing = stronger wind.

An arrow with a speed shows the system's direction and speed of motion (kt).

Pointing into the wind (i.e. wind comes from the end with the feathers). Feathers encode speed:

Calm
< 1 kt

5 kt
half feather

10 kt
full feather

25 kt
2 full + 1 half

50 kt
pennant (solid triangle)

65 kt
pennant + full + half

0/8 clear

1/8

4/8 scattered

6/8 broken

8/8 overcast

sky obscured

A compact plot of one weather station's full observation. Each position encodes one variable.

Circle fill = cloud cover in octas (see above).
Wind barb points into the wind. Half-feather = 5 kt, full = 10 kt, pennant = 50 kt.
Top-left = temperature (°C or °F depending on country).
Bottom-left = dewpoint. Small T–Td spread = humid/fog risk.
Top-right = SLP in tenths of mb, last 3 digits only. Prefix "9" if < 500, else "10". So 124 = 1012.4 mb, 984 = 998.4 mb.
Bottom-right = 3-hour pressure trend. +12/ = rose 1.2 mb (trace shape follows). Minus sign = falling.