Global Winds and Ocean Currents

Flashcards covering vocabulary terms related to global winds and ocean currents.

Ocean Currents Formation

Wind blowing over oceans causes surface water to drift, creating pressure differences that drive currents hundreds of meters deep. Wind patterns globally initiate major surface currents. Winds = Primary driver of surface ocean currents.

Heat Redistribution Role of Surface-Ocean Currents

Transfer heat from tropics (energy surplus) to polar regions (energy deficit), balancing Earth's energy imbalance (~40% of heat transport in the Northern Hemisphere comes from the movement of surface ocean currents).

Climate Impact

Without currents, temperature differences between latitudes would increase drastically, altering global climate.

Warm Currents

Originate in the tropics, where water is heated by intense sunlight. Flow poleward, carrying warm water into cooler regions. Warmer than surrounding waters at higher latitudes. humidifying and warming effect on the east coasts of continents

Cold Currents

Originate in high latitudes (polar/subpolar zones) or from upwelling (deep, cold water rising). Flow equatorward, bringing cold water into warmer regions. Cooler than surrounding waters at lower latitudes. drying and cooling effect on the west coasts of the landmasses

Gyres

Major surface currents form large, circular systems called gyres, centered around subtropical high- pressure zones.

Coriolis effect

gyres flow clockwise in NH and anticlockwise SH; surface currents do not cross the equator; they mirror their flow on either side.

North/South Equatorial Currents

Tropical waters near the equator are carried westward by trade winds.

Regional Climates and Ocean Currents

Ocean currents moderate local climates. For eg: the North Atlantic Drift keeps northwestern Europe milder than other regions at similar latitudes.

Desert Formation and Cold Currents

Cold currents like the Benguela and Peru Currents suppress rainfall along western coasts, contributing to the formation of deserts such as the Namib and Atacama. These currents cool the air above, making it stable and dry—preventing cloud formation and precipitation.

Upwelling

cold currents along west coasts in subtropical latitudes are frequently reinforced by upwelling; trade winds drive the surface waters offshore.

ENSO

El Nino-Southern Oscillation; a single climate phenomenon that has 3 phases it can be in – two opposite phases, “El Niño” and “La Niña” or “Neutral” (neither El Niña or La Niña)

Southern Oscillation

connection between surface pressure readings at weather stations on the E and W sides of the Pacific noted that when there is a rise in pressure in E Pacific, fall in pressure in W Pacific and vice versa

El Nino

warming phase of ENSO; Southern Oscillation swings in the opposite direction – pressure increases in the W Pacific and decreases in the E Pacific

La Nina

cooling phase of ENSO; if the trades become exceptionally strong, then unusually cold surface water extends over the eastern and central Pacific, and warm water and rainy weather are confined mainly to the western tropical Pacific

North Atlantic Oscillation (NAO)

Refers to large scale changes in pressure that occur naturally in the North Atlantic region; describes changes in pressure between the Azores (subtropical) High and the Icelandic (subpolar) Low

Positive NAO index phase

higher than average pressure in the Azores High and lower than average pressure in the Icelandic Low, increased pressure difference between the two systems – stronger winter storms, occurring more often and following a more northerly track

negative NAO index phase

weak Azores High and weak Icelandic Low, smaller pressure gradient between these two systems will weaken the westerlies resulting in fewer and weaker winter storms