You might have heard the phrase “weather pattern” on the news but what is it? A weather pattern means days where it is hot or cold for a long time like summer and winter. There are events that can change the weather. Some volcanoes emit - or send out - so much volcanic ash that less of the sun’s energy is able to reach the surface of the Earth. This event changes the weather pattern because the entire planet cools off. This doesn’t happen very often. There are two events that happen every few years that affect weather patterns. These two events are named El Niño and La Niña. Both can be responsible for severe weather like blizzards, extreme cold and heat and yes, tornados, hurricanes and typhoons.

Both El Niño and La Niña are weather patterns that originate, or begin, in the Pacific Ocean along the equator. Scientists call them The El Niño Southern Oscillation, or ENSO. Oscillation means repeating an event or change at regular times. El Niño and La Niña are opposing patterns. One is driven by warmer temperatures in the Pacific Ocean and the other by cooler water. El Niño translates into English as Little Boy and La Niña is Little Girl. The name is Spanish. It makes sense that the phenomenon has Spanish names because it was Spanish fishermen who settled in Peru in the 1500’s who first noticed this weather change.

El Niño occurs when water temperatures rise in the Pacific Ocean. The change is only three to five degrees. La Niña is the opposite, meaning the water cools down. As the Pacific Ocean’s temperature rises during an El Niño cycle, winds that circle the planet high in the atmosphere slow down and the warmer water moves east, toward the coast of North, Central and South America. During La Niña, the winds become strong and blow away from the Americas toward Asia. Both patterns cause it to be dryer and warmer in some places, or cooler and wetter than normal in others. Depending on where you are, these weather changes can cause flooding, blizzards or drought. These temperature changes also cause large storms to form not just over land but out in the ocean causing more hurricanes than normal. This is not part of global warming and is just a natural process.

As the Pacific water warms up or cools down, life in the ocean changes as well. Animals that stay in cooler waters migrate and warmer water marine life moves into their place. Even the largest of the sea animals, the whales, are affected. In places where the cool water animals have moved away, whales have to change their migration pattern in order to find fish or krill to eat.

The NOAA, or National Oceanic and Atmospheric Administration, has set buoys across the Pacific Ocean to measure wind, water currents, humidity and temperatures. The buoys act like remote science labs and send information to scientists and scientific exploration boats all around the world. They study this data, to determine if an El Niño or a La Niña is coming. Using that information, along with information from weather satellites, helps them predict the weather where you live.