Sea Science: by Jordanna Sheermohamed
While there are the large-scale global winds that circumnavigate the Earth, there are seasonal and geographically influenced wind patterns that happen on smaller scales too. Regardless of the scale size, winds are a function of forced movement of air. This can occur as a function of temperature differences, pressure differences or height differences.
Mountain and valley breezes are examples of micro-scale weather patterns that are produced in a manner very similar to that of onshore breezes – including sea breeze, which results from uneven heating between the land and the water, forcing flow onshore.
Down-sloping winds, known as katabatic winds, can be gravity driven, or even driven by temperature/density difference. Examples of these winds can be found in Greenland, California and the fjords of Norway. The up-sloping winds, referred to as anabatic winds, are winds that are heated from the surface and forced to rise to higher elevations.
Regional patterns, such as the dry and warm Santa Ana winds of Southern California, are often named with a nod to the region and are often heavily woven into the folklore of the local cultures.
The Mediterranean region has several regionally named wind patterns that are due to the numerous mountains that circle the sea.
The mistral, for example, refers to a strong, cold and northwesterly wind that blows from the southern region of France into the northern portions of the Mediterranean.
The etesian – which get its name from the Greek word estesios, meaning “annual” – is an annual summer wind that blows over parts of Greece and the Aegean Sea.
The bora is a northeastern wind that blows over the Adriatic Sea, similar to the bora wind over the Black Sea basin.
The ostro, a southerly wind over the Adriatic and Mediterranean Sea, is a humid and warm wind that drags moisture inland and aids in precipitation in the area.
The levanter, or solano, seen in this photograph, is another Western Mediterranean Sea wind. It’s an easterly wind that blows through the Straits of Gibraltar and is a result of the winds blowing through a gap in the mountains. The name comes from the French word levant, meaning “to raise,” in reference to the rising sun from the East.
While the scale, the location and the culturally flavored name of these various wind patterns may differ, however, the science behind each of the winds remains the same.
Jordanna Sheermohamed is president and lead meteorologist of Weather Forecast Solutions, a weather-forecasting firm (WeatherForecastSolutions.com). Comments are welcome below.