headerfoto_1
headerfoto_1

Super Flexible Layout Builder

Tons of ElementsReal Drag and DropFullscreen OptionUndo/Redo functionallity

Meteorological Terminology

To simplify the description of weather, meteorologists use very specific terminology.

Wind strength: The Beaufort Scale

wind speed (kts) descriptive term sea state in open water and max. wave height (in m,)
0 <1 calm mirror-like
1 1-3 light air ripples 0.1
2 4-6 light breeze small wavelets 0.3
3 7-10 gentle breeze some breaking crests 1
4 11-16 moderate breeze fairly frequent white horses 1.5
5 17-21 fresh breeze many white horses and possibly spray 2.5
6 22-27 strong breeze extensive white horses and spray 4
7 28-33 near gale foam begins to form streaks downwind from crests 5.5
8 34-40 gale well – marked foam streaks 7.5
9 41-47 severe gale tumbling crests, spray may effect visibility 10
10 48-55 storm sea surface generally white with foam 12.5
11 56-63 violent storm wave crests blown into froth, forming long white patches on surface 16
12 >64 hurricane air filled with foam and spray, surface white, visibility badly affected >16

The wind speed refer to sustained wind speed (at 10 m above the surface), not to transient gusts which may be considerably stronger.

Note that the sea state descriptions are a guide to what may be expected in the open sea: the Beaufort scale should not be used to describe sea states, and you should bear in mind that conditions may be very different in coastal waters.

Sea State

*crest to trough

code descriptive term wave height (m)*
0 calm-glassy 0
1 calm-rippled 0 – 0.1
2 smooth 0.1 – 0.5
3 slight 0.5 – 1.25
4 moderate 1.25 – 2.5
5 rough 2.5 – 4.0
6 very rough 4 – 6
7 high 6 – 9
8 very high 9 – 14
9 phenomenal >14

Visibility

Different terms are used to describe visibility, depending on the context – land, sea, or air.

marine aviation & coastal land
>5 NM good
2 – 5 NM moderate
1 km- 2 NM poor
1 km- 2 km mist or haze
200m- 1 km fog fog fog
50-200m thick fog
<50m dense fog

Timing

Timing can be crucial, especially if you are looking for a ‘weather window’ in which to make a dash for home.

time from issue of forecast
imminent < 6 hours
soon 6 – 12 hours
later > 12 hours

Movement of weather systems

slowly < 15 knots
steadily 15 – 25 knots
rather quickly 25 – 35 knots
rapidly 35 – 45 knots
very rapidly > 45 knots

Pressure Changes

change in past 3 hours
steady > 0.1 mb
slowly 0.1 – 1.5 mb
rising or falling 1.6 – 3.5 mb
quickly 3.6 – 6.0 mb
very rapidly > 6.0 mb
now rising a previous trend has reversed, and pressure is now rising or now falling
now falling

next

Onze zeilschool

Impressie

Geweldige zeilcursus van Jim, hij kent de kneepjes van het vak en weet dit goed over te brengen!

MatthijsCursist

FAQ

Veelgestelde vragen

Lees meer

HANDIG

Handigheidjes en wetenswaardigheden

Lees meer

RYA TRAININGEN

Overzicht van alle RYA trainingen

Lees meer