The wind is caused by a depression or anticyclonic situation.
In the context of a low pressure situation, the winds blow counterclockwise, in a direction that tends to return towards the center of the low pressure area.
Conversely, in the presence of an anticyclonic flow, the wind will blow clockwise, with the tendency to move away from the center of the anticyclone.
On nautical charts the wind is represented by vectors (arrows) which can be accompanied by flagpoles indicating the strength of the wind; for example, 2 flagpoles represent a speed of 20 knots.
The state of the sea:
The weather reports also communicate the state of the sea and the height of the waves in meters. As a rule, the height of the wave motion is also indicated, since it too can represent a danger. This height is rated on a Beaufort scale from force 0 (calm) to force 12 (hurricane).
In weather reports, precipitation is indicated like this: fog, mist, frost, drizzle, rain, snow, hail, storm, thunderstorm, tornado, dew and ice.
Navigation can be particularly tough in hail conditions, and especially in poor visibility. Each of these conditions is represented by a different color on the card.
The weather reports also indicate the tide times. The times of low and high tide are accompanied by the height of the water. Before leaving or returning to the port it is essential to know the height of the water, and the necessary calculations differ according to the high or low tide.
For those equipped with electronic navigation software, these values are represented by colored triangular hourglasses; the tip of the upper triangle indicates the rising tide, the downward point the ebbing tide. The divergences between the tides determine the action of the current. It is easier to reenter an estuary with a rising tide, as the tidal current will pull the boat in the right direction.