Parts of Los Angeles received a storm powered by an atmospheric river hit the state. Known as a ‘river in the sky’, the weather phenomenon can produce torrential amounts of rain.

What are Atmospheric Rivers?

• Atmospheric rivers are relatively long, narrow regions in the atmosphere – like rivers in the sky – that transport most of the water vapour outside of the tropics.
• Size: Atmospheric rivers can be between 400 and 600 kilometres wide. They can be over 1,600 kilometres long.

• Atmospheric River Formation:

  • Atmospheric rivers usually begin over tropical regions. Warm temperatures cause ocean water to evaporate and rise into the atmosphere. Strong winds help to carry the water vapour through the atmosphere.

  • As atmospheric rivers move over land, the water vapour rises up farther into the atmosphere. It then cools into water droplets, which fall as precipitation.

• Impacts:

  • Heavy rainfall associated with ARs can cause flooding, landslides and mudslides.

    • They can also lead to water supply disruption, and develop drought-like conditions.