The doldrums and the horse latitudes are two interesting terms used by meteorologists and sailors to describe two distinct areas over the ocean. Although they share the calm wind characteristic, they are located on two different degrees of latitude and display different characteristics of climate and weather.
Calm winds, warm temperatures and very convective thunderstorms are used to describe the doldrums. Located at zero degrees latitude, also known as the equator, you will find this described area over the ocean. Here, there is little change in temperature and pressure in the horizontal direction but vertically is a different story. The warm air at the surface rises and condenses into large towering cumulonimbus clouds that then turn into highly convective thunderstorms. This is an area where the northeast trade winds in the northern hemisphere and the southeast trade winds in the southern hemisphere converge. This converging air at the surface collides and then lifts all the warm, moist air on the surface. That air then condenses and forms a line of strong convection and energy called the Inter Tropical convergence zone. There is so much energy and moisture here despite its relative calmness. Boats travelling in this area may experience bouts of calm weather and then quite the opposite when they are met with loud thunder and lightning.
Moving on up the ladder to an area of even calmer settings; located at 30 degrees north, you will find an area over the ocean that is famously known as the horse latitudes. This area, like that of the doldrums, is characterized by calm wind and small changes in horizontal temperature and pressure. The difference between this area and the doldrums, is that the westerlies and northeast trade winds diverge. This means the winds flow away from this area rather than converge and create thunderstorms. Storms are very scarce here as compared to the doldrums. It’s very calm. For example, if you were sailing to the new world back in the 1400s, you would find that your boat would come to a complete halt. With no winds to push the sails, sailors would be stranded for a long time in this area as they calmly drifted. What made this area take on its famous name was while sailors were stranded, they would run low on supplies and end up having to eat their horses or throw them overboard to make the ship lighter.
The doldrums and horse latitudes are a interesting couple of places to find yourself sailing overseas. Thankfully, today we have advanced in our shipping and travel. Many boats have engines that can tug them along in the horse latitudes and a lot of coverage from heavy rain and storms in the doldrums. Regardless of advances in shipping, these areas are significant when travelling overseas; an experience sailors will never forget.
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© 2019 Meteorologist Alex Maynard