*The apparent wind is the wind that is perceived on a moving sailboat. It is made up of the true (the actual prevailing) ambient wind and the vehicle’s airstream and is decisive for many settings, such as sail position and sail trim, on the sailing vehicle¹. The apparent wind is always earlier than the true wind¹. The faster a sailboat sails, the more forward the apparent wind¹.
(Link to the calculation: Calculate apparent wind (rechner.club)
Source: Conversation with Bing, 27.7.2023
(1) True and apparent wind – Wikipedia. https://de.wikipedia.org/wiki/Wahrer_und_scheinbarer_Wind.
(2) What is apparent wind and how does it affect sails? – SegelPlanet. https://segelplanet.de/was-ist-scheinbarer-wind/.
(3) Courses to the wind – Wikipedia. https://de.wikipedia.org/wiki/Kurse_zum_Wind.
Trade winds are moderately strong and very steady winds that occur in the tropics or subtropics up to about 30° latitude around the globe1. The average wind speed of the trade winds is around 10-15 knots (18-28 km/h).
In Europe, the winds generally blow from a westerly direction and are referred to as westerly winds ¹⁴⁵. The westerly winds are part of the Ferrel cell, one of the three major wind cycles in each hemisphere ¹. The Ferrel cell is located between the Hadley cell at the equator and the polar cell at the poles ¹. The winds in the westerly wind zone blow at an average speed of 20 to 30 km/h ¹⁴. Please note that wind speed may vary depending on location and weather conditions.
Source: conversation with Bing, 6.11.2023
(1) The global wind system – Planet School. https://www.planet-schule.de/mm/die-erde/Barrierefrei/pages/Das_globale_Windsystem_planetarische_Zirkulation.html.
(2) Westerly wind zone – Wikipedia. https://de.wikipedia.org/wiki/Westwindzone.
(3) Why does the wind blow predominantly from the west? – SWR Wissen. https://www.swr.de/wissen/1000-antworten/warum-weht-der-wind-ueberwiegend-aus-westen-100.html.
(4) In which direction does the wind blow? – Mahnazmezon. https://bing.com/search?q=aus+which+direction+does+the+wind+blow+in+our+latitudes+of+Europe+mainly%c3%a4chly+and+in+what+strength+on+a+average%3f.
(5) Which way is the wind blowing? – Mahnazmezon. https://www.mahnazmezon.com/articles/science/which-way-does-the-wind-blow.html.
(6) undefined. https://bing.com/search?q=.
Apparent wind (calculator)
Scheinbaren Wind berechnen (rechner.club)
**The Flettner rotor is a rotating cylinder that is exposed to the wind. It acts like a sail and generates a force perpendicular to the air flow due to the Magnus effect. It is named after Anton Flettner, who had it patented as a ship propulsion system. The Flettner rotor is mainly used on rotor ships. Rotor propulsion alone is not possible, as it offers neither propulsion nor maneuverability in calm conditions1.
*** Flettner rotor – Wikipedia
https://de.wikipedia.org/wiki/Flettner-Rotor#Windkraftanlagen_mit_horizontaler_Achse
The wind speed usually increases with increasing height, as the friction caused by buildings, trees and other obstacles on the ground reduces the wind speed. At a height of about 50 m, the wind speed is often higher than on the ground, but the exact increase depends on various factors, such as the roughness of the terrain and atmospheric conditions.
A common method for estimating the wind speed at a given height is the logarithmic wind profile formula:
Calculations of wind force, depending on height
The wind speed usually increases with increasing height, as the friction caused by buildings, trees and other obstacles on the ground reduces the wind speed. At a height of about 50 m, the wind speed is often higher than on the ground, but the exact increase depends on various factors, such as the roughness of the terrain and atmospheric conditions.
A common method for estimating the wind speed at a given height is the logarithmic wind profile formula:
V(h) = V_0 \times \left( \frac{\ln(h/z_0)}{\ln(h_0/z_0)} \right)
]Where is:
- ( V(h) ) is the wind speed at the desired height ( h ),
- ( V_0 ) is the wind speed at the reference height ( h_0 ) (e.g. 10 m),
- ( z_0 ) the roughness length of the terrain.
For open terrain, the wind speed at a height of 50 m can be about 30-50 % higher than on the ground. In urban areas or forests, the increase may be less.
If you need a more precise calculation for a specific environment, I can help you find the right values! 😊
Translated with DeepL.com (free version)
Berechnungen der Windstärke, abhängig von der Höhe
Die Windstärke nimmt mit zunehmender Höhe in der Regel zu, da die Reibung durch Gebäude, Bäume und andere Hindernisse am Boden die Windgeschwindigkeit reduziert. In etwa 50 m Höhe ist die Windgeschwindigkeit oft höher als am Boden, aber die genaue Zunahme hängt von verschiedenen Faktoren ab, wie der Rauigkeit des Geländes und den atmosphärischen Bedingungen.
Eine gängige Methode zur Abschätzung der Windgeschwindigkeit in einer bestimmten Höhe ist die logarithmische Windprofilformel:
[
V(h) = V_0 \times \left( \frac{\ln(h/z_0)}{\ln(h_0/z_0)} \right)
]
Dabei ist:
- ( V(h) ) die Windgeschwindigkeit in der gewünschten Höhe ( h ),
- ( V_0 ) die Windgeschwindigkeit in der Referenzhöhe ( h_0 ) (z. B. 10 m),
- ( z_0 ) die Rauhigkeitslänge des Geländes.
Für offenes Gelände kann die Windgeschwindigkeit in 50 m Höhe etwa 30–50 % höher sein als am Boden. In städtischen Gebieten oder Wäldern kann die Zunahme geringer ausfallen.
😊