### History of Wind Gust Measurement Techniques  
Many anemometer types used today were invented already in the 18 th and 19 th Centuries [12]. The first known anemometer was proposed by [PERSON] in Italy already in 1450. It was a swinging-plate anemometer, which consisted of a disc hanging at the end of a vertical shaft. The disc was placed perpendicular to the wind, and the wind speed measurement was based on the angle between the disc and its original position [13]. In 1667, [PERSON] developed a similar device, called [PERSON]'s anemometer. In 1744, [PERSON] proposed a similar device without knowing these earlier versions of the anemometer. His anemometer consisted in addition of a spring catch that showed the maximum force caused by the wind [12]. This instrument probably provided the first measurement of wind gusts ever. Pressure plate anemometers were still used during the first half of the 20 th Century [14,15], but after that, other instruments have taken over. Another category of pressure anemometers is comprised of pressure tubes. The first one was introduced by [PERSON] in 1732 to measure flow velocity in water. Following [PERSON]'s theoretical work (1738) on relating the flow velocity to the difference between the total and static pressure in the tube, it was possible to measure velocities using the Pitot tube both in liquid and gas [16]. In meteorology, the pressure tube anemometer was not applied until 1775, when [PERSON] introduced his anemometer. It consisted of a U-shaped tube, whose one limb was bent over towards the wind. By mounting this limb to a vertical spindle, the U-tube formed a direction vane. After [PERSON], different types of pressure-tube anemometers were introduced, but their difficulty was in the recording. Only the mean wind speed could be obtained as the fluctuating wind speed caused only very small changes in the scale of the manometer. The first self-recording pressure tube was introduced by [PERSON] in 1892. It included pens that recorded both the wind speed and direction. For the first time, it was possible to have also records of wind gusts and lulls, although there were difficulties in obtaining good pen-marking at high wind speeds and in very gusty conditions [16]. [PERSON] pressure tube required a stable surface, and therefore, it was not possible to use it for example at sea. In 1936, [PERSON] introduced a differential anenoid recorder to obtain a more complete record of gusts and lulls than by the float recorder of [PERSON] pressure tube [16]. Today, pressure tube anemometers are mainly used in aircraft and in wind tunnels as reference measurement systems. In aircraft, the most widely-used pressure tube anemometer is the five-hole probe, which can provide high-frequency measurements of all three wind velocity components when the orientation and the speed of the aircraft are known. Like pressure anemometers, the first rotating anemometers were also introduced in the 18 th Century [12]. In the beginning, they resembled wind mills. In 1846, [PERSON] introduced the first cup anemometer [17], which is similar to those still in wide use in the fields of meteorology and especially in wind energy. The [PERSON]'s cup anemometer consisted of four cups, but later, a three-cup version became more popular because of its aerodynamic characteristics [16]. The size, shape and design of the cups and the arm lengths and the respective aerodynamic effects on the rotation characteristics have received much theoretical and experimental focus (e.g., [18; 19]), and methods to better understand the anemometer performance and dynamic response to wind speed fluctuations are still being developed further (e.g., [20; 21]). Over the years, the cup anemometers have achieved an accuracy acceptable for wind energy [22; 23], where the accuracy is highly important as the wind power is proportional to wind speed cubed [7]. The first acoustic anemometers were not based on the speed of sound in the air, but were rather composed of an organ that produced different tones with varying wind speed and direction [12].