India, March 7 -- A World Meteorological Organisation (WMO) update on March 6 said that the ongoing La Nina - it is a cyclical cooling of the equatorial Pacific Ocean that has a cooling effect on global average temperature - that began in December was likely to end after the February-April season. Is it unusual for the event to be this short? The short answer to this question is that the length of the ongoing La Nina is indeed somewhat unusual. However, the answer also depends on how one defines the event. Here is why.

As the brief answer above suggests, it is important to understand what La Nina is before checking whether the current La Nina is an unusually short one. So what is La Nina? While the short description for La Nina given abo...