Good morning interweb: how to construct ocean currents. First
a map; oceans, continents, winds. Close to the equator draw in two currents flowing to the West.
Split these currents whenever a continental shelf is mesh; equatorward... poleward.
The equator in full will loop back around to form an equatorial counter current moving eastward. Split the flow of the shelf and
boom
We've just created and closed our first ocean gyre between 30 and 45 degrees north and south
The Western is kicking and will drag her currents eastward.
Once again, split the flow up the shelves,
the equator our flow will close our tropical gyres, and the poleward flow will begin our next set.
The Easteries kicking around 60 to 75 degrees north and south, and would blow the currents westward.
Split the flow at the shelves and close those loops.
Finally, if you have an open ocean at any of the poles drop in a westward flowing circumpolar current and if there are any gaps,
fill them in with smaller gyres or simply by logically extending existing
currents
Note that the red currents are warm
Blue are cold and black are neutral. That is, warm currents carry warm water from lower latitudes to higher latitudes,
blue currents carry cool water from higher latitudes to lower latitudes, and black currents are a kind of neutral.
No significant heat exchange is occurring as they travel more or less
Latitudinally. Anyways, check to see if all the loops are closed and that the spin directions all makes sense
Like if one gyre spins clockwise the other should spin counterclockwise then clockwise then counterclockwise
You get the idea basically, think of your oceans the system of interconnecting years and you can't go wrong.
So there you go, ocean currents, done! That said, if your planet is not exactly like Earth you'll need to alter things slightly
like, if your planet spins in the opposite direction to earth (retrograde), flip all the currents like so; if it has a single
circulation cell per hemisphere it will have less gyres,
but they'll be larger. This for pro-grade spins and this for retrograde spins.
Three circulation cells per hemisphere equals earth; pro-grade,
retrograde. Five cells per hemisphere will produce smaller gyres and more of them;
pro-grade, retrograde; and the same deal with seven cells per hemisphere just more. So again pro-grade,
retrograde. If this all sounds like gibberish check out the linked video. The underlying logic here
is that a current will change direction somewhere between the start and midpoint of each cell.
So the more cells you have, the more the winds will change direction, the more gyres will be created.
Now if your planet is a water world
It will be banded; think Jupiter, but with water. Protip, though
If you grind down some of your continents such that they are just below sea level, you get the aesthetic of a water world
but with the currents of an earth-like planet.
Because remember the currents are defected at the continental shelf, not the actual
continents. If we were to tightly lock our water world, we'd end up with a sort of spaceship looking
ocean encased in ice, with two big gyres in either hemisphere.
Once we introduce continents the same rules from earlier apply: split the flow when a continental shelf is hit, and close loops.
Now that we've mapped our currents let's talk effects.
Obviously ocean currents will affect seafaring societies
Explorers from the western continent might discover the eastern continent way before these nearby islands, just by sailing
downwind and following the currents. Or, they might do what the early Polynesians did and sail upwind.
The idea being that if something went wrong on the voyage, it would be easy to get back home quick.
This is one of the reasons why Polynesians arrived in the likes of Hawaii and the Easter islands literally hundreds of years before they reached
relatively nearby, New Zealand
So ocean currents can be both oceanic highways and road blocks
Depending on how a society deals with them. In terms of climate, ocean currents will cause latitudinal variations. Compare
Florida and the Baja, California peninsula:
both lie on the same latitude yet one is dry and harsh and the other is wet and
Super hot
The culprit: ocean currents. Cold water means cold air which means less evaporation less clouds and less rain.
So whenever cold currents flow along land masses, cooler, drier coastal conditions are created.
The reverse is true of warm currents: warm water means more evaporation. So expect wetter warmer coastal conditions
It's worth noting these areas on your map. In addition, expect cool coastal waters to be very nutrient-rich.
These will be your world's fishing hotspots. And,
expect coral reefs to form anywhere in the tropics where warm currents flow. To finish up,
let's talk En-So events. En-So, short for El Nino Southern Oscillation, is an irregularly
periodic variation in winds and sea temperatures that occurs in the Pacific Ocean.
It has three main phases: a neutral phase, and then La Nina and
El Nino, both of which can last for several months, vary in intensity, and typically occur every few years. In the neutral phase, or
normal phase, the trade winds blow across the
Pacific. These winds push warm water across the
Pacific piling it up in the West and drawing cool water up in the East via a mechanism called upwelling.
The temperature differences causes air to rise in the West and sink
in the East, creating a huge circulation system known as Walker Circulation. In the La Nina phase
Everything gets turned up to 11
trade winds blow harder, more warm waters piled up in the West,
more cold waters drawn up through the depths in the east, the temperature difference increases, making the Walker circulation
stronger, causing trade winds to blow even harder again and boom:
Feedback loop engaged. La Nina brings storms of flooding to West and heat waves and droughts to the east in the El Nino
phase, everything reverses.
The trade winds weaken allowing warm water to drift back towards the east; this breaks down the Walker circulation,
causing the trade winds to blow even weaker, allowing more water to gather in East, and oh
would you lookit, we got ourselves another feedback loop; just everything has flipped.
El Nino brings heat waves and droughts to the west, and storms and flooding to the east.
So if your world has a large open ocean
akin to the Pacific, expect equatorial land masses on its periphery to be subject to ENSO events.
And, bear in mind, the directions will flip if your planet has a retrograde spin. And there you go: ocean currents, their effects, and
construction done!
Good morning web the last Q&A went really well
so
How about we do another Q&A?
if you have any questions about this video in particular or just any of my videos in general
A world building or con laying leave them in the comments and I'll get to recording a Q&A
Thank you all so much for watching especially. Thanks crawl to the patrons Isaac silver
Robin hilton world anvil rip to pass a and john career each and every one of you are awesome. I'm until next time Edgar