Everyone is familiar with the term ocean and current but most of the people do not know about doldrums. Furthermore, it is a common phenomenon that the sailor around the world is very familiar with. Generally, this is found near the equator region.
What are Doldrums?
Doldrums is a natural phenomenon that happens near the equator. In addition, it is an oceanic belt that circles around the globe.
The region has low atmospheric pressure and lack of a significant amount of wind. Also, the weather in the region is cloudy and rainy.
This zone or region is often known as the convergence zone or ITCZ (Intertropical Convergence Zone). Besides, they approximately lie between five degrees north and five degrees south latitude.
Moreover, due to earth’s axis tilt the extent slightly shift towards south during the winter of the northern hemisphere. On the contrary, it slightly shifts towards the north during the summer of the northern hemisphere.
Relation of Global Wind Circulation
They fit perfectly in the global pattern of the atmospheric circulation of wind that involves three cells in each hemisphere.
Also, the cells involve zones of major wind belts, separated from each other by zones of relatively lighter winds in which the air sinks or rises.
In addition, they separate the trade winds of the southern hemisphere from the trade wind of northern hemisphere.
At the doldrums, the warm air rises and flows away from the equator to about 30 degrees south and north latitude where it descends respectively.
From this wind, some of the warm air moves towards the westward direction in the form of trade winds. On the contrary, the remaining portion blows towards the east, creating the dominant westerlies.
After that, the air again rises to around 60 degrees in latitude from the boundary between westerlies and the polar easterlies and finally sinks once more at the poles.
Effects on Weather
They affect the rainfall in many equatorial regions that cause a wet and dry season of the tropics rather than the cold and warm season of higher latitudes. In addition, the longer-term of doldrums can cause conditions like drought or flood in nearby areas.
Moreover, the doldrums becomes narrow while moving away from the equator. In that condition, it can be interpreted as a front along the foremost edge of the equatorial air.
Besides, the cycle appears to be a 15 to 25 day in thunderstorm activity along with the doldrums. Also, it is of the half-wavelength of Madden-Julian Oscillation (MJO).
Characteristics of Doldrums
The doldrums lies in the regions of the Pacific and Atlantic oceans that have little winds.
There is no wind in that are so sailing by propelling of wind is not possible. And without the engine, the problem could be deadly.
In addition, doldrums is a cause of solar radiation from the sun that directly beams down on the area around the equator.
Due to the heating up the warm air rises vertically rather than blowing horizontally.
In the region, there is no wind for weeks.
They exist a little north to the equator, but the effect can be felt from 5 degrees north to 5 degrees south of the equator.
Also, the trade wind borders them from both south and north.