Writer: Huang Xiaotong.
He is a graduate student at the Chinese Academy of Meteorological Sciences.
2023-24 Clipper Ocean Race "Zhuhai" Ambassador Crew.
Hello Captain! Now that you have a sail-powered sail and a loyal crew, and you're about to embark on a round-the-world voyage, how do you plan your course? From which port and on which day? These decisions are not made by feeling. Sailing on the vast sea, basic meteorological knowledge can ensure the safe navigation of the sailboat to the greatest extent, riding the wind to reach the other side. Today, I will take the route planning of a round-the-world sailing event that is currently underway as an example to talk about the background of atmospheric circulation and its impact on navigation.
spring 2024
The Clipper Ocean Race is one of the most influential sailing events in the world and is the largest amateur round-the-world sailing event. Since its inception in 1996, nearly 6,000 crew members from more than 60 countries and industries have participated in the Clipper Ocean Race. In the 2023-24 season, eleven boats set sail from Portsmouth, England, through eight stages, visiting all continents except Antarctica, and circumnavigating the world for almost a year. Two of the ships were sponsored by Chinese cities, namely "Zhuhai" and "Qingdao".
The back of the fleet. 
Qingdao. 
Zhuhai. 
Meteorological trivia
First, let's take a look at the sailboat's preference for wind. In ocean voyages, the sailors' favorite wind directions were side downwind and crosswind, that is, the wind coming from the back or side of the ship; Less popular is the windward, that is, the wind coming from the side of the ship; And when the headwind, that is, the wind comes directly in front of the ship, the sailboat cannot move forward at all.
Different wind directions can be different for a boat's performance.
cFirst stage
Europe - East Coast of South America
The first leg of the route.
At the beginning of September, we set off from the south of the UK and sailed down from the north and northeast winds on the east side of the North Atlantic high, passing through Europe and the west coast of Africa. After coming to the equatorial windless zone, drift in the calm wind for a few days, use the local wind of the tropical cumulus convection, approach the southern hemisphere, until you catch the southeast trade wind in the southern hemisphere, you can approach the South American continent, and take the northeast wind on the west side of the South Atlantic high pressure, sail south along the east coast of South America, and reach Uruguay.
cSecond stage
East coast of South America - Cape of Good Hope, Africa
Stage 2 route
In mid-October, we set off from Uruguay to start our journey across the South Atlantic. As soon as we set out, we headed south to find the prevailing westerly winds on the south side of the South Atlantic high. However, due to the fluctuating westerly winds, it is often difficult to encounter a steady westerly wind during this stage, often dodging cyclone after cyclone and heading east to reach the southernmost tip of Africa.
c. Third stage
Cape of Good Hope, Africa - West Coast, Australia
Stage 3 Route
In mid-November, we set off again from South Africa, skirting the Cape of Good Hope and embracing 40 degrees south latitude. Since the high-latitude oceans of the Southern Hemisphere are not blocked by land, the prevailing westerly winds often bring huge wind and waves, which have become characteristic of the Southern Ocean. We chased the cyclone, going back and forth between the crest and the bottom of the two-story building. The entire trip was almost entirely a pleasant tailwind, and after crossing 6 time zones, we turned north for a crosswind ride into the Australian summer.
cFourth stage
West Coast of Australia - East Coast of Australia
Stage 4 Route
In December, in the middle of summer in the Southern Hemisphere, we set off on a journey to skirt half of Australia. The southern side of this stage is still dominated by cyclones, and once you get around Tasmania to the east coast, the wind direction has little to do with the multi-year average. Also be careful to avoid the warm currents that push the fleet back from the north side.
cFifth stage
East Coast of Australia - South Asia
Stage 5 Route
After departing from the east coast of Australia, ride the small tail of the southeast trade winds and enter the equatorial windless zone again. This time it was already summer in the Southern Hemisphere, and the equatorial windless belt was also located in the Southern Hemisphere. After a few more days of fluttering, we can finally catch the northeast trade winds of the northern hemisphere and sail all the way wide and unhindered to the Luzon Strait. After crossing the strait, it follows the northeast monsoon of the Asian winter to Vietnam, then Zhuhai, Guangdong, China.
c. Sixth stage
East Asia-West coast of North America
Stage 6 Route
In the spring of the northern hemisphere, we set out from Zhuhai and first went north to Qingdao in the northeast monsoon. Fortunately, it is already spring, and the monsoon is no longer as good as it was in the middle of winter. And because it is not the season when typhoons are active, there is no need to worry about the unpredictable and dangerous typhoons on this part of the voyage. Qingdao was the last stop before the fleet crossed the North Pacific. From here, we still ride the northeast monsoon that surrounds East Asia to bypass Japan from the south, and then meet with the westerly winds sandwiched between the North Pacific High and the Aleutian Low as soon as possible, check the westerly wind belt in the Northern Hemisphere, and sail downwind to the west coast of North America, Seattle, USA.
cSeventh stage
West Coast of North America - Panama Canal - East Coast of North America
Stage 7 Route
Summer is again in the Northern Hemisphere, and this time we set out from the west coast of North America, riding the northerly winds from the east side of the North Pacific High to the south, followed by a cross-equatorial airflow from the Southern Hemisphere that will do us a small favor and send us to Panama. After visiting the Panama Canal, we work with the northeast trade winds of the Atlantic Ocean and go all the way north, plus the southwest monsoon in the summer of the North American continent, to reach Washington on the east coast.
c. Eighth stage
East Coast of North America - Europe
Stage 8 Route
The last stage is the journey back to the home port. In the middle of summer, starting from the east coast of North America, along the north side of the North Atlantic high pressure, all the way to the wind, eastward across the North Atlantic, to Scotland, and then from the east back to Portsmouth, England, the round world journey is over.
Meteorological trivia
While most of the circulation systems we've mentioned are permanent and don't seem to be very picky about timing, the reality is more complex than the multi-year averages we've mapped. Imagine navigating the angry Southern Ocean in the southern hemisphere winter, or navigating the monsoon zone in the northern hemisphere summer, keeping an eye out for typhoons and not catching the westerly winds in the southern part of the Aleutian depression. In short, although the current route planning will inevitably encounter no wind or a small part of the windward range, it ensures the safety of navigation to the greatest extent in the background of meteorological circulation.
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