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What are Doldrums?

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The "doldrums" is a nautical word for the belt around the Earth above the equator where sailing ships will get stuck in windless waters sometimes. Low atmospheric pressure and a lack of substantial wind characterize the region. In addition, the region's weather is cloudy and rainy.

The convergence zone, or ITCZ (Intertropical Convergence Zone), is the name given to this zone or region. Furthermore, they are precisely situated between the latitudes of five degrees north and five degrees south. The Doldrums are a few degrees north of the equator, but their impact can be felt anywhere from 5 degrees north to 5 degrees south. This was a particular concern for sailors who relied on the wind to power their ships in the past. It was a crisis with the potential to be deadly.

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The hot, moist air is drawn up into the atmosphere like a hot air balloon due to extreme solar heating above the equator. When the air rises, it cools, resulting in a ring of showers and storms around the Earth's center. In the horse latitudes, where the air travels downward toward the Earth's surface, the increasing air mass finally subsides. In the ITCZ, there is typically no surface wind since the air circulates upward. This is why the region will keep sailing ships at bay for weeks. That's why it's known as the doldrums.

Characteristics of Doldrums

  • Since there is no wind in that region, sailing by wind power is not feasible. And without the engine, the problem might be deadly.

  • The doldrums are by the sun's direct solar rays beaming down on the region near the equator.

  • They exist only north of the equator, but the effect can be felt anywhere from 5 degrees north to 5 degrees south of it.

  • The doldrums are situated in the Pacific and Atlantic Ocean regions with little winds.

  • Thanks to the heating up, the heated air rises vertically instead of blowing horizontally.

Effects on Weather

They have an effect on rainfall in many equatorial areas, allowing the tropics to have a rainy and dry season rather than the cold and warm seasons in higher latitudes. Furthermore, the longer-term consequences of the doldrums may result in drought or floods in surrounding areas.

The average winds within the ITCZ are light, in comparison to the trade winds that feed the areas north and south of the equator. Because of the steady, stagnant, or inactive winds, sailors in the eighteenth century called this belt of calm the doldrums as trans-equatorial sea voyages became more frequent.

Role in Tropical Cyclone Formation

One of the six conditions for tropical cyclogenesis is low-level vorticity, which the ITCZ offers as a region of wind shift and speed, also known as horizontal wind shear. Increasing Coriolis force makes the development of tropical cyclones within the ITCZ more likely as it migrates to tropical and subtropical latitudes, and even beyond, during the respective hemisphere's summer season.

Fun Facts

  • There's no wind here.

  • The ITCZ's exact location gradually changes with the seasons. Since convection is limited by the distribution of ocean temperatures, the seasonal cycle is subtle across the oceans.

  • The Doldrums have a special role in maritime culture, with a reputation for being a potentially dangerous region where ships can be trapped for weeks at a time, running out of food and water.

  • Since sunlight shines down directly on the region above the equator, the Doldrums are caused by solar rays from the sun.

  • The Doldrums are infamous for being irritatingly slow, but it's not just because of the stagnant steady winds. It will periodically change erratically between numerous weather patterns, including destructive thunder and electric storms.

FAQ (Frequently Asked Questions)

1. Why is the Name ‘Doldrums’ Used for Equatorial Pressure Belts?

Ans: The equator is parallel to 0-degree latitude. The equatorial area is directly vulnerable to the blazing hot sun's rays. Throughout the year, the degree of heat or warmth is exceptionally high. The air gets lighter as it grows hotter. As a result, the light air in and near the equator increases, resulting in the development of a low-pressure region. On the other hand, the opposite process is at play, resulting in the creation of high-pressure zones. The earth's crust is classified into seven pressure zones in total.

2. During the Summer in the Northern Hemisphere, Which Way Does the Doldrums or ITCZ Move?

Ans: During the summer season in the northern hemisphere, the doldrums move north due to the tilt in the earth's axis.