A deep east-west overturning in the atmosphere normally confined to within about 20 degrees latitude of the equator extending from low-levels to near the tropopause. One side of the Walker Circulation is associated with rising motion, clouds, and rain while the opposite side with sinking motion, generally fair weather and little or no rain. This circulation is large in spatial extend normally extending anywhere from way around the world or completely around the world (thus either 1 or 2 upward and 1 or 2 downward branches to the circulation). The rising and sinking branches are climatologically anchored to specific geographical locations, but these locations are seasonally dependent. In winter the the rising branch is centered near the "maritime continent" of greater Indonesia while in summer it is centered near southern India. The sinking branches are generally found in the eastern equatorial Pacific in winter and summer. Sub-branches of rising motion are generally tied to equatorial areas of South America and Africa in summer.
The Walker circulation is an atmospheric circulation of air at the equatorial Pacific Ocean, responsible for creating ocean upwelling off the coasts of Peru and Ecuador. This brings nutrient-rich cold water to the surface, increasing fishing stocks. It was discovered by Jacob Bjerknes in 1969 and was named after the English physicist Sir Gilbert Walker who discovered the Southern Oscillation.