What's an Ocean Gyre?

A few years ago, the Gulf Stream swiftly carried me home from the Bahamas while simultaneously tormenting me with waterspouts. It got me thinking...
Author:
Updated:
Original:

A few years ago, the Gulf Stream swiftly carried me home from the Bahamas while simultaneously tormenting me with waterspouts. It got me thinking: cruisers often consider currents when determining where to sail, when to leave, and the how best to get there, but what about the bigger picture? 

Here are four things to ponder when sailing (or planning to sail) in the gyres of the North Atlantic and Pacific Ocean. 

Gyres are currents that flow in a circular pattern around the periphery of the major oceans. They are driven by wind and pressure gradients, and directed by the Coriolis effect, which explains how the Earth’s rotation deflects objects. For example, in the North Atlantic, westerly winds push water east across the North Atlantic. Blocked by Europe, the water accumulates until it has more pressure than the surrounding water, so a pressure gradient forms and the water wants to flow down. The Coriolis effect comes into play and makes the water flow south, forming the Canary Current. This pattern continues around the periphery of the ocean, forming a circle of currents called a gyre. 

There are five gyres in the world: North Pacific Gyre, North Atlantic Gyre, South Pacific Gyre, South Atlantic Gyre and Indian Ocean Gyre. All northern hemisphere gyres flow clockwise and all southern hemisphere gyres flow counterclockwise, thanks to the rotation of the Earth. 

Western Boundary Currents are found on the western side of ocean basins and are the deepest and fastest currents. The western boundary current in the North Atlantic is the Gulf Stream. It carries warm water from the equator to northern latitudes to be cooled. Eastern Boundary Currents, such as the California Current, are slow and shallow and carry cool polar water south toward the equator.

Currents moderate the world’s climate by circulating heat from the equator. For example, The Canary Current brings cool northern water south to absorb tropical heat and the Gulf Stream carries warm water back to the poles where it is cooled. This helps the Earth maintain a moderate temperature. Ocean gyres also explain why cities near the same latitude, such as Oakland, California, and Washington DC, have such different climates. Oakland stays cooler in the summer because of the cool air above the California Current while the air above the Gulf Stream warms Washington DC and turns its summers into scorchers.

Related

01A-LEAD-Finished-table

DIY: A Better Saloon Table

The original saloon table in my Down East 45 schooner was a single heavy sheet of 3/4in laminated plywood, 27in wide by 57in long. It was supported on two substantial aluminum pedestals locking into a set of large round collars screwed to the sole. There were two annoying ...read more

02b-screen-shot

Salty Dawgs Recognized by CCA

The Salty Dawg Sailing Association (SDSA) has long been the go-to organization for high value, affordable rallies, but when Covid forced the sudden closure of borders in the Caribbean, it pivoted to organizing the Homeward Bound Flotilla. Its experience organizing rallies came ...read more

FB-BHM-1024

SAIL Black History Month Series: James Forten

James Forten was born on September 2, 1766 in Philadelphia to free Black parents Thomas and Margaret Forten. Forten attended a Quaker school as a young child, then went to work with his father who was a sailmaker. His father died when he was still young, and Forten worked ...read more

sailme-app_ SAIL

5 Ways Sail.me Helps You Monetize Your Boat

Ready to earn some extra funds by renting out your boat or yacht? Sail.me is an interactive service that allows you to monetize your boat in a secure, safe, and easy way. A user-friendly app and website will help you manage reservations, add-ons, and set customized routes to ...read more

VendeePromo

2020-21 Vendée Timeline

As a spectator event, France’s Vendée Globe never disappoints, and the 2020-21 edition of the quadrennial round-the-world race was no exception. From equipment failures to climactic rescues, heartbreaking abandonments and a breathtakingly close finish, this edition, which ...read more

valleytrunk3

BVI Chartering in the Pandemic

The week before I flew out to the British Virgin Islands for a bareboat charter, I was having a few second thoughts. The islands had broken out of their Covid-enforced tourism hiatus in December, but the conditions of entry seemed a little stringent: a negative Covid test within ...read more

01-LEAD-windfarm

Sailing Amid Offshore Wind Farms

Here in Europe, the general feeling about green energy from offshore wind turbines has moved on after an initial surge of general skepticism. Concerns raised over cost, threats to seabirds, wind interference and the rest have to some extent been answered, and it’s hard to argue ...read more

LunaRossaPrada

VIDEO: Luna Rossa Wins the Prada Cup

The show has gone on despite last week's Covid panic in Auckland, and the "underdog" Italians are victorious. After being bested by INEOS Team UK in the round robin section, they seemed to have an uphill battle ahead of them going into the finals. However, the Italians have been ...read more