# Waves, how waves form

The saltwater movement of the seas and oceans is called surf because each of the individual waves is called wave.

Knowing this movement well in advance is sometimes of vital importance. However, due to the amount of factors that affect the waves, such as the strength and directionality of the winds, proximity to the Moon, strength and directionality of the sea currents, the thermal radiation of the sun, ... among others; surface wave movement (what is generally known as sea ​​state) It is very complex.

By influencing so many variables of complicated evaluation and affecting so many inhabitants who work at sea, it is common that radio and television forecasts are added about the state of the sea during the weather.

In a very simplified way, we can say that two types of waves intervene mainly in waves: those of local origin, originated by the prevailing wind system, with the height of the waves increasing proportionally to the intensity of the wind (this type of state of the sea is said windy sea) and those due to other distant factors, for example, a strong storm whose huge waves have spread great distances (called swell).

Usually two things usually happen. If the sea of ​​wind and the sea of ​​the sea are in the same direction, the waves overlap, increasing the frequency of the waves and alternating waves of greater height (sea in the background) with lower waves (sea of ​​wind). When the swell of the two types occurs in an area, but in a different direction it is said two band sea.

## Douglas scale measures the swell

In general, the scale of Douglas is used to assess the state of the sea, which takes its name from the surname of English Vice Admiral Henry P. Douglas (he created it in 1917). It consists of 10 degrees depending on the height of the waves. It is the following, with its corresponding degree and denomination:

 Degree Denomination Wave height (meters) 0 Calm sea Without waves 1 Flat sea Between 0 and 0.25 2 Curly sea Between 0.25 and 0.50 3 Marejadilla Between 0.50 and 0.75 4 Surge Between 0.75 and 1.15 5 Thick sea Between 1.15 and 2 6 Very thick sea Between 2 and 3 7 Wooded sea Between 3 and 5 8 Mountainous sea Between 5 and 10 9 Confusing sea More than 10

The Douglas scale does not classify ten types of seas, but measures the states of the sea by ten degrees, from the time it is resting until it reaches giant waves of 14 meters or more.

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