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		Find out about the phenomenon behind La Niña, the extensive cooling of the central and eastern Pacific.	Key Points La Niña translates from the Spanish as "The Child Girl". La Niña refers to the extensive cooling of the central and eastern Pacific. Increased sea temperatures on the western side of the Pacific means that here the atmosphere has more energy and the frequency of heavy rain and thunderstorms is increased. Typically La Niña will last for up to 12 months and will be a generally less damaging event than the stronger El Niño. Also in BBC Weather Drought Disclaimer The BBC is not responsible for the content of external websites.

	Between 1997 and 1998 the damage caused by the El Niño Southern Oscillation was catastrophic for many parts of the world, but is there another threat that causes headlines around the world as scientists learn more about 'La Niña' (or cold episode southern oscillation)? What is this phenomena? La Niña translates from the Spanish as "The Child Girl" and meteorologically is the opposite of the more well known El Niño. The term La Niña refers to the extensive cooling of the central and eastern Pacific. The subsequent changes to the atmosphere and ocean circulation are as varied and diverse as those of the earlier El Niño event. Increased sea temperatures on the western side of the Pacific means that here the atmosphere has more energy... Lower than normal temperatures across the central and eastern Pacific Ocean have important effects on the weather and in particular on rainfall amounts. Increased sea temperatures on the western side of the Pacific means that here the atmosphere has more energy and the frequency of heavy rain and thunderstorms is increased. Places like north Australia, Papua New Guinea and Indonesia will have more cloud and more rain, (the opposite to the dry weather during El Niño and the problem with smog and bush fires). The strong temperature contrast across the Pacific means the easterly trade winds will be enhanced for the Pacific Ocean. La Niña is preceded by the build up of cooler than normal subsurface water in the tropical Pacific. Wave action and easterly winds will pull this colder water to the surface off the coast of Peru and Ecuador and as the easterly trade winds strengthen the effect becomes stronger. La Niña does not always follow an El Niño event but there is some correlation between a swing back to normal conditions and an initial weak La Niña being set up. Typically La Niña will last for up to 12 months and will be a generally less damaging event than the stronger El Niño, that is not to say that the global impact will not be as diverse. The Atlantic and Pacific hurricane activity will increase with La Niña... Globally La Niña, in very general terms, will mean that those parts of the world that normally experience dry weather will be drier and those with wet weather will be wetter. The Atlantic and Pacific hurricane activity will increase with La Niña and the effects of severe droughts are likely in those already dry parts of the world. Broadly speaking, the La Niña event could give drier conditions in Central East Africa, SW USA, Northern Mexico, South America etc. Wetter conditions could be experienced in North/North East Australia, South Africa, Southern Asia (during the monsoon) and the northern half of South America, Central America and the Hawaiian Islands. Whilst historically these are the effects of a La Niña event, as we have seen with El Niño, nothing is certain and the global impact is still to be fully understood.

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La Niña