«La Niña» comes from Spanish and means «the girl». If you speak any Spanish, you’ve probably noticed it.
However, this statement is not about a girl, but about the weather event «La Nin / A».
The weather event brings with it high air pressure differences, which in turn ensure that the weather is influenced.
La Niña formation – simply explained
The feature for the weather phenomenon La Nin / Aare above average air pressure differences between Indonesia and South America. In South America, the air pressure is much higher than in Indonesia.
A high air pressure brings with it good weather and prevails as soon as there are many air particles in a small space. the trade winds try to compensate for the high air pressure difference.
trade winds are steady, moderately strong winds in the tropical sea areas.
To find out more about the topic of trade winds, simply click on the explanation of «trade winds».
If you are now wondering how the trade winds can ensure that the differences in air pressure are balanced, here is the answer to your question:
The intensified trade winds drive the warm surface waters of the Pacific from the coast of South America further into Southeast Asia. Overall, the Pacific coast stretches across Australia, New Zealand, East Asia and the west coast of North and South America.
As water flows westward (Southeast Asia) into the eastern Pacific Ocean, cold deep water rises along the coast of South America to compensate for the loss.
This process creates a significant difference in water surface temperature between the eastern and western Pacific Ocean. The temperature difference is up to 10 °C.
The result is a cooled down atmospheric circulation, the one teleconnections of the Atlantic.
In meteorology, the teleconnection understood as a connection between weather processes in two distant areas. The relationships relate, among other things, to the opposing behavior of the air pressure.
You’re probably wondering now what the Walker circulation and how it stands in the context of the La Nina weather phenomenon. The Walker circulation is one wind circulation, where air masses circulate in opposite directions. Different forms of the Walker Circulation are El Niño and La Niña.
More about the Walker circulation and El Nino can be found in the accompanying explanation.
You can see the Pacific Ocean between the coast of Southeast Asia in the west and the coast of Peru in the east. Warm and humid air rises and rain falls on the coast of Southeast Asia.
The higher the air rises, the faster and stronger it cools. Above a certain height, it is directed east again, where the air then sinks and the cycle closes.
Due to the direction of the wind, the water also circulates, so the cold water on the coast of Peru is pushed up and the water temperatures on the west coast of Southeast Asia are high.
Effects of La Niña
The effects of La Niña are not as severe as El Niño. Nevertheless, there are some consequences of this weather phenomenon:
- The water in the western Pacific is warming at the surface. This ensures that more rain falls on the Australian north coast.
On the one hand, the air expands at high temperatures and a high pressure area develops, which brings good weather with it. On the other hand, low temperatures ensure that low pressure areas form, which in turn cause rain. Since both sides in the cycle are mutually dependent, contrary weather conditions must prevail in each case.
- In Southeast Asia, La Niña also heavy rain that can trigger landslides.
- In North America, the occurrence of hurricanes is favored by La Nina and its associated air pressure conditions.
- It rains less in South America.
Record rainfall in late 2010 in the north-east Australian state of Queensland and in northern New South Wales led to flooding covering roughly half the area of the state of Bavaria. in the ssouthwest Australia, on the other hand, experienced an extreme drought that had never been seen before was previously observed.
Episodes of La Niña worldwide
The effects of La Niña also extend beyond the Pacific region. While it will remain mostly dry in East Africa, precipitation will increase in southern Africa and in the Sahel zone from Ghana to Sudan. The typical of India monsoon rain can also be stronger.
In North America, droughts are increasing in the southern United States and Mexico, while the weather is becoming wetter between Canada and the northern portion of the United States, particularly around the Great Lakes bordering Canada and the United States.
La Nina in Europe
Impacts of La Niña in Europe include the polar vortex.
polar vortex are areas of low pressure caused by different air densities. In such a polar vortex, cold air sinks and causes an increase in air pressure on the ground.
These effects arise because more heat in the higher the atmosphere is transported. The low one is responsible for this air pressure and more tropical cyclones in East Asia.
The polar vortex in turn influences the weather in Europe. However, since these processes are extremely complicated and also influence each other, it is clear that La Niña influences the weather in Europe in part, but not in exactly what way. Thus, the influence of the weather phenomenon La Nina remains unexplained in places.
La Nina – The most important thing
- La Nina is that counterpart from El Nino.
- What defines La Niña is them above average high air pressure differences between Indonesia and South America, which ensures that the trade winds become stronger.
- The stronger trade winds, in turn, ensure that the Walker circulation increases, but also cooled becomes.
- the consequences are essential lower than El Niño, but still noticeable.
- Effects of La Niña in Europe are for example the polar vortex.
- The polar vortices in Europe have in turn influence on the weather in Europe.