What are Atmospheric Rivers?
Atmospheric rivers in very simple terms are rivers of water vapor in the sky. Like rivers on land, that transport water, rivers in the sky transport water vapor, as rivers change direction and intensity of flow due to obstacles and geographical changes, rivers in the sky move with the weather, carrying roughly the same quantity of water as rivers on the ground.
Atmospheric rivers come in many shapes and sizes, however the largest atmospheric rivers are responsible for extreme snowing and rainfall. Pineapple Express is an example of a strong atmospheric river (The Pineapple Express is a narrow region of atmospheric moisture that builds up in the tropical Pacific) that is capable of bringing moisture from tropics near Hawaii over the U.S. West Coast.
Atmospheric rivers are key features of the global water cycle, they are long flowing regions of the atmosphere about 250–375 miles wide and can be more than a 1000 miles long. They pick up water vapour from the warm, moist air of the tropics and they drop the water as rain or snow in cooler regions of the land.