Wind Ratings & the Beaufort Scale

Understanding the Beaufort Wind Scale: Navigating Nature's Gusts

In the age of modern meteorology, where high-tech instruments and satellites provide real-time data on weather patterns, it's easy to forget the humble origins of wind measurement. Long before the invention of anemometers and sophisticated weather models, sailors and observers relied on simple yet effective methods to gauge wind strength. One such method, still used today, is the Beaufort Wind Scale.

Origins and Development

Named after Sir Francis Beaufort, an Irish hydrographer in the British Royal Navy, the Beaufort Wind Scale was first introduced in the early 19th century. Its purpose was to standardize the estimation of wind speed for naval purposes. Beaufort's original scale ranged from 0 to 12, with each number corresponding to a specific description of the wind's effect on the sea.

Scale Breakdown

The Beaufort Wind Scale describes wind speeds based on observed conditions rather than precise measurements. We find it a helpful tool to be able to visually observe what's happening, and work out what we need to do.

Here's a simplified breakdown:

• 0 (Calm): Smoke rises vertically. The sea surface is smooth like a mirror.
• 1 (Light air): Direction of wind is shown by smoke drift, but not by wind vanes. Ripples with the appearance of scales are formed, but without foam crests. Wind speed is 1-5km/h, or 1-3 knots.
• 2 (Light breeze): Wind can be felt on the face; leaves rustle; ordinary vanes moved by the wind. Wind speed is 6-11 km/h, or 4-6 knots.
• 3 (Gentle breeze): Leaves and small twigs are in constant motion; light flags extended.  Wind speed is 12-19 km/h, or 7-10 knots.
• 4 (Moderate breeze): Raises dust and loose paper; small branches begin to move; wind extends light flag.  Wind speed is 20-28 km/h, or 11-16 knots.
• 5 (Fresh breeze): Small trees in leaf begin to sway; crested wavelets form on inland waters.  Wind speed is 29-38 km/h, or 17-21 knots. 
• 6 (Strong breeze): Large branches in motion; whistling heard in telegraph wires; umbrellas used with difficulty.  Wind speed is 39-49 km/h, or 22-27 knots.
• 7 (Near gale): Whole trees in motion; inconvenience felt when walking against the wind.  Wind speed is 50-61 km/h, or 28-33 knots.
• 8 (Gale): Twigs break off trees; the wind generally impedes progress.  Wind speed is 62-74 km/h, or 34-40 knots.
• 9 (Strong gale): Slight structural damage occurs (chimney pots and slates removed).  Wind speed is 75-88 km/h, or 41-47 knots.
• 10 (Storm): Trees uprooted; considerable structural damage occurs.  Wind speed is 89-102 km/h, or 48-55 knots.
• 11 (Violent storm): Widespread damage; very rarely experienced inland.  Wind speed is 103-117 km/h, or 56-63 knots.
• 12 (Hurricane): Devastation occurs.  Wind speed is 118+ km/h, or 64+ knots.

Most wind testing is done in very controlled circumstances, and often tested 'to destruction' with permanent in-ground fixtures supporting the umbrella. So while it is very useful when designing products to know how strong your umbrella is and what they can withstand, testing 'to destruction' is not an every day level of use. So while wind testing is a good tool, it's not the only measure of 'what good looks like' when choosing the right patio umbrella for you and your situation.

It's important to note that patio umbrellas are temporary shade structures and should be used with care. It's all well and good for people to claim that their umbrellas are good in 100km/h+ winds, but common sense tells us that they should never be up in that level of wind. Personally, I wouldn't want to be sitting in a violent storm, and it certainly won't be doing your umbrella any good!

Do you have a windy or exposed site? 

Our patio umbrellas are commercially proven, used in coastal hospitality venues nationwide.

For windy and exposed sites, we also offer re-inforced frame options to provide additional strength when exposed to sustained strong winds. Get in touch to chat about the options available for your venue.