The Seasonal and Periodicals Winds

By Seasonal and Periodic winds, we mean those that always blow in the same direction, periodically reversing the trend. It can happen:

  • Daily. As with the breezes that follow the thermal variations between day and night, and
  • Seasonally. It is a trend in the summer and winter when high-pressure zones are born in previously low-pressure zones.

Breezes are those periodic daily winds that blow near the coasts, reversing their direction over a day. During the day, as a result of solar heating, the layers of air above the mainland heat up more rapidly than those above the sea, thus forming areas of high pressure on the sea and low pressure on the continent and the consequent wind blowing towards land (sea breeze). During the night, the rapid cooling of the mainland causes a cooling of the air more significant than that which occurs at sea and the high pressure is formed above the continent, creating the consequent wind that blows towards the sea (land breeze).

Examples of periodic seasonal winds are monsoons, winds characteristic of the Indian Ocean and the China Sea. The monsoons blow during the summer semester from the ocean towards the Asian continent from areas of high pressure to areas of low pressure. They reverse their direction when high and low-pressure regions invert during the winter.

In fact, in summer, the Asian continent heats up sensitively, creating a depression area that recalls the warm and humid air of the ocean. In winter, the opposite happens because the continent cools much faster than the ocean. Typhoons, violent tropical cyclones, often accompany this seasonal change due to the displacement of enormous air masses.

Sample of a Weather Routing Chart.

The climate associated with monsoons is:

  • wet and rainy in the summer – when the wind blows from the sea towards the mainland;
  • dry in the winter – when it blows from the land towards the sea.

We distinguish periodic winds from Constant and Variable winds. Constant winds always blow in the same direction and orientation. Variable winds change direction and orientation, while Periodic winds only change direction.