Calm
Calm or lull designated on the Beaufort scale , the size zero . It can be recognized by the smoothness of large water surfaces and restricts the exchange and mixing of air masses on land. Inversion weather conditions and fine dust pollution can develop .
Emergence
Since swell and swell are caused by the wind, they decrease during longer periods of calm (initially the swell, only much later the swell, provided there is no wind in adjacent areas) and water surfaces can finally become mirror-like. On smaller water areas where there is no swell (ponds, lakes, sheltered bays, etc.), this effect occurs accordingly much faster and more often.
Long periods of calm on the water have always been a major problem for sailing ships, especially on the open sea; often food spoiled and water supplies ran out, which then meant illness or death for a large part of the crew. Seafaring songs still tell of this today, e.g. B. Hamborger Veermaster or We lay before Madagascar . Joseph Conrad describes a terrible lull in the story Die Schattenlinie .
The first remedy was created by the use of rowers in antiquity - until modern times this remained the only alternative drive at sea and it was only with the help of the engines that the situation changed fundamentally.
Today almost every sailing yacht and every multi-master at sea has at least one auxiliary engine, which is tellingly often referred to colloquially as a lull .
Relative calm (i.e. lack of apparent wind ) prevails whenever there is movement in the direction of the wind at wind speed. B. on boats with a slight tail wind (at the same speed) under motor. If the motor is to be used to assist with a slight tailwind on sailboats, the apparent (i.e. perceived on the boat) wind and thus the sailing performance, which is ultimately zero in "relative calm", decrease accordingly; In this case, the boat ultimately runs completely under engine power, with a correspondingly high fuel consumption, since the sails are ineffective due to the lack of wind.
Tropical cyclones
In the eye of a tropical cyclone there is almost no wind, while the highest winds occur on the eye wall, which can reach speeds of more than 300 km / h.
Calm sea areas
- Horse widths between the trade wind areas and the west wind areas of the northern and southern hemispheres
- Kalmen in the area of the equator
