How do ocean currents work? - Jennifer Verduin

Translator: Julie Mbeyella Reviewer: Nelson Simfukwe

In 1992,

Mwaka 1992

a cargo ship carrying bath toys got caught in a storm.

Meli ya mizigo iliyobeba shehena ya Vichezeo vya kuogea ilipatwa na dhoruba.

Shipping containers washed overboard,

Makontena ya kusafirishia shehena yakapotea kwenye maji,

and the waves swept 28,000 rubber ducks and other toys into the North Pacific.

Mawimbi yalisomba bata wa raba na vichezeo vinginevyo kwenye bahari ya Pacific ya kaskazini.

But they didn’t stick together.

Lakini havikukaa pamoja.

Quite the opposite–

Tofauti kabisa--

the ducks have since washed up all over the world,

Bata hao wametapakaa Dunia nzima,

and researchers have used their paths

Na wachunguzi wametumia njia yao

to chart a better understanding of ocean currents.

Kuelewa zaidi mikondo ya Bahari.

Ocean currents are driven by a range of sources:

Mikondo ya bahari inaendeshwa na vitu vingi:

the wind, tides, changes in water density,

Upepo,mawimbi,mabadiliko kwenye wiani,

and the rotation of the Earth.

Na mzunguko wa Dunia.

The topography of the ocean floor and the shoreline modifies those motions,

Topografia ya sakafu ya bahari na ufukwe vinaongeza hiyo mizunguko,

causing currents to speed up,

Kusababisha mikondo iongeze spidi,

slow down, or change direction.

Kupunguza spidi au kubadili muelekeo.

Ocean currents fall into two main categories:

Mikondo ya bahari imegawanyika kwenye makundi makuu mawili:

surface currents and deep ocean currents.

Mikondo ya juu na mikondo ya ndani ya bahari.

Surface currents control the motion

Mikondo ya juu ina dhibiti mwendo

of the top 10 percent of the ocean’s water,

Wa asilimia 10 ya maji ya bahari,

while deep-ocean currents mobilize the other 90 percent.

Wakati mikondo ya ndani inadhibiti asilimia 90 iliyobaki.

Though they have different causes,

Japo yanasababishwa na vitu tofauti,

surface and deep ocean currents influence each other

Mikondo ya juu na ya ndani inashabiana

in an intricate dance that keeps the entire ocean moving.

Ni dansi ambayo inaifanya bahari itembee.

Near the shore,

Karibu na fukwe,

surface currents are driven by both the wind and tides,

Mikondo ya bahari ya juu inaendeshwa na upepo na mawimbi,

which draw water back and forth as the water level falls and rises.

Ambayo inavuta Maji ndani na Nje pale ambapo kiwango cha maji kinapungua na kuongezeka.

Meanwhile, in the open ocean, wind is the major force behind surface currents.

Wakati huo huo,kwenye bahari upepo ndio nguvu kubwa ya mikondo ya juu.

As wind blows over the ocean,

Upepo unapovuma juu ya bahari,

it drags the top layers of water along with it.

Unaenda na maji ya juu,

That moving water pulls on the layers underneath,

Maji yanayotembea yavuta vilivyomo chini,

and those pull on the ones beneath them.

Na hizo zinavuta za chini yake.

In fact, water as deep as 400 meters

Maji yenye kina kirefu cha Mita 400

is still affected by the wind at the ocean’s surface.

Bado yana athiriwa na upepo wa juu ya bahari.

If you zoom out to look at the patterns of surface currents all over the earth,

Ukiangalia kwa karibu muundo wa mikondo ya juu ya bahari ya Dunia nzima,

you’ll see that they form big loops called gyres,

Utaona kwamba inatengeneza vitanzi vikubwa vinavyoitwa gyre,

which travel clockwise in the northern hemisphere

Inayosafiri upande wa saa kaskazini mwa ulimwengu

and counter-clockwise in the southern hemisphere.

Na kwa kurudi kusini mwa ulimwengu.

That’s because of the way the Earth’s rotation

Hiyo ni sababu ya jinsi Dunia inavyozunguka

affects the wind patterns that give rise to these currents.

Inaingilia muundo wa upepo inayoleta hii mikondo.

If the earth didn’t rotate,

Kama Dunia isingezunguka,

air and water would simply move back and forth

Maji na hewa vingeenda mbele na nyuma

between low pressure at the equator

Kutoka sehemu yenye presha ndogo ikweta

and high pressure at the poles.

Na presha kubwa kwenye fito.

But as the earth spins,

Lakini Kadri Dunia inavyozunguka,

air moving from the equator to the North Pole is deflected eastward,

Hewa kutoka ikweta kwenda kwenye fito ya kaskazini inageukia mashariki,

and air moving back down is deflected westward.

Na hewa inayoelekea chini inageukia magharibi.

The mirror image happens in the southern hemisphere,

Tofauti yake inatokea kwenye ulimwengu wa kusini,

so that the major streams of wind

Ili kusudi mito mikubwa ya upepo

form loop-like patterns around the ocean basins.

Inatengeneza miundo ya vitanzi karibu na mabonde ya bahari.

This is called the Coriolis Effect.

Hii inaitwa ifekti ya coriolis.

The winds push the ocean beneath them into the same rotating gyres.

Upepo unasukuma bahari chini yake kwenye gyre za kuzunguka.

And because water holds onto heat more effectively than air,

Na sababu maji yanashika moto upesi kushinda hewa,

these currents help redistribute warmth around the globe.

Hii mikondo inasaidia kugawanya joto duniani.

Unlike surface currents,

Tofauti na mikondo ya juu,

deep ocean currents are driven primarily by changes in the density of seawater.

Mikondo ya ndani inaendeshwa na tofauti ya wiani wa maji ya bahari.

As water moves towards the North Pole,

Maji yanavyoelekea fito ya kaskazini,

it gets colder.

Yanakuwa na baridi.

It also has a higher concentration of salt,

Pia yanakuwa na chumvi nyingi,

because the ice crystals that form trap water while leaving salt behind.

Sababu ile barafu inayoshikilia maji wakati inaacha chumvi nyuma.

This cold, salty water is more dense,

Haya Maji ya baridi yenye chumvi ni mazito zaidi

so it sinks,

Kwahiyo yananuka,

and warmer surface water takes its place,

Na Maji ya uvugu vugu yanachukua nafasi yake.

setting up a vertical current called thermohaline circulation.

Kutengeneza mkondo wa wima unaoitwa mzunguko wa thermohaline

Thermohaline circulation of deep water and wind-driven surface currents

Mzunguko wa thermohaline wa maji ya ndani na yanayoendeshwa na upepo wa Mkondo wa bahari wa juu

combine to form a winding loop called the Global Conveyor Belt.

Unajiunga kutengeneza kitanzi cha upepo kinachoitwa Global Conveyor Belt.

As water moves from the depths of the ocean to the surface,

Maji yanavyohama kutoka ndani ya bahari kwenda juu.

it carries nutrients that nourish the microorganisms

Yanabeba virutubishi ambavyo vinasaidia kukuza viumbe hai

which form the base of many ocean food chains.

Ambayo inatengeneza msingi wa cheni nyingi za chakula baharini.

The global conveyor belt is the longest current in the world,

Mkondo wa Global Conveyor belt ndo mrefu zaidi duniani,

snaking all around the globe.

Ukizunguka dunia nzima.

But it only moves a few centimeters per second.

Lakini unazunguka sentimita chache kwa sekunde.

It could take a drop of water a thousand years to make the full trip.

Inaweza ichukua tone la maji miaka 1000 kufanya safari yote.

However, rising sea temperatures are causing the conveyor belt

Japokuwa Levo za joto la bahari zinazopanda zinasababisha ukanda wa conveyor

to seemingly slow down.

Kupunguza spidi.

Models show this causing havoc with weather systems

Modeli zinaonesha hii inasabisha ma tatizo kwenye hali ya hewa

on both sides of the Atlantic,

Kwenye pande zote za Atlantic,

and no one knows what would happen if it continues to slow

Na hamna anayejua nini kitatokea ikiendelea kupunguza spidi

or if it stopped altogether.

Au ikisimama kabisa

The only way we’ll be able to forecast correctly and prepare accordingly

Njia pekee tutakayoweza tabiri sawasawa na kujiandaa vizuri

will be to continue to study currents and the powerful forces that shape them.

Ni Kwa kuendelea kusoma mikondo na nguvu zote zinazosababisha mikondo kuwepo.