Useful reminders about measuring wind speed and direction
Let's start by recalling what wind is in meteorology to start on a solid basis. The wind is simply the horizontal movement of air.
Wind measurement is composed of two complementary parameters: its speed (or force) and its direction. The units of measurement of wind used in the UK are km/h or m/s for its speed, and knots (1 knot = 1.852 km/h) which are mainly used by sailors and pilots.
Important: when we talk about the direction of the wind, we are talking about its cardinal origin (north for example), where it comes from, and not where it is going (even if the nuance is not necessarily obvious).
The wind is not constant, which is why we speak of "instantaneous wind", "average wind" and gusts. This is because the wind speed and direction at a particular location vary enormously from one second to the next. In weather forecasting, the instantaneous wind is therefore measured for 3 seconds, while the average wind is calculated over a period of 10 minutes.
What about the gusts? These are in fact sudden increases in the instantaneous wind speed, exceeding the symbolic speed of 10 knots, or 18 km/h. But it is not only the wind speed that changes abruptly during a gust, its direction also changes, sometimes up to 45° compared to the average wind.
Did you know that wind direction is determined by a pressure difference? Without going into detail, this is an interesting point.
Finally, it should be noted that wind speed increases with altitude, which is why the wind is often stronger on a mountain (besides the fact that the surroundings are clear).
Now that you know (almost) everything about wind speed and direction, let's move on to the measurement of these variables in the UK.
Measuring wind speed
How can you measure wind speed on y our own?
To find out exactly how fast the wind is blowing in your garden, there are some very effective devices. The anemometer is the reference device for measuring wind speed and is perfectly complemented by the wind vane which is able to indicate the direction of the wind.
These can be found in the shops at very affordable prices, but there are also more elaborate and technologically advanced models for better measurement of wind speed and direction. These include the anemometer and the connected wind vane, which link directly to a connected weather station.
The connected devices are not more accurate because their measurement of wind speed and direction remains the same, but it is their use that is simplified. It becomes possible to access data on one's digital devices, compile information, or make weather forecasts.
And the meteorological Service?
National meteorological services do not use a different method or equipment than private individuals to measure wind speed (and even direction).
The anemometer and wind vane remain on the programme, after all, they are the reference instruments. However, these are professional models, more imposing, more technologically advanced, and fixed to the top of masts 10 metres above the ground for open measurement.
With your own devices, you can pretend to be a meteorological service!
To benefit from a practical, precise, and efficient measurement of wind speed and direction, couple the Netatmo Intelligent Anemometer to the Netatmo Intelligent Weather Station. Knowing everything about the wind from your living room has never been easier.
The Beaufort scale for wind measurement without an instrument
The Beaufort scale or Beaufort wind force is a table that makes it possible to roughly estimate the wind speed. This is not an exact measurement, but it does not require a measuring device.
The principle of this scale is to analyse the effects of the wind on people, trees, and others in order to deduce its average speed. For example, let's look at some of the first degrees of the Beaufort scale.
If the wind speed in m/s is 0, you are at degree 0 on the Beaufort scale, i.e. you do not feel the wind and the smoke rises vertically. Degree 1 is reached when the smoke indicates the direction of the wind and can be felt slightly, its speed is then 1 to 1.5 m/s.
The 3rd degree implies that the leaves are continuously waved outside, that the flags are unfurled, and that the wind blows at a speed of 3 to 5.5 m/s.
Degree 6 on the Beaufort scale indicates a wind speed of between 10.5 and 14 m/s: the wind can be heard whistling through the wires and even the largest branches of the trees start to shake.
As for the 8th degree, it indicates a storm approaching because it becomes difficult to walk facing the wind, the branches break… danger is present. And for good reason, the wind blows at a force of between 17.5 and 20 m/s.
Valuable indications, therefore, but not very precise.
The measurement of wind speed and direction has been going on for centuries. Today, it is possible to do this with great precision and in a rather practical way.