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Why does lightning strike? And answers to 50 other weather questions

  • How does weather affect asthma?

    High heat, humidity, cold, rain, thunderstorms, or any sudden weather changes can make asthma worse, according to the Asthma and Allergy Foundation of America. Because extreme events are more problematic than milder weather, climate change is likely to worsen asthma symptoms.



  • How can it rain when it’s sunny?

    A sun shower can happen if the atmosphere is unstable. Temperature changes can push air up and down, which can create the right circumstances for rain. The sky may look empty because “the air in the sinking columns suppresses clouds, creating areas of clear skies between the showers,” explained The New York Times.



  • Why do earthworms show up after it rains?

    After rainfall, it’s common to see worms wriggling around on the pavement. Scientists used to think it was so these crawlers wouldn’t drown. But worms can breathe through their skin, so they need moisture. Experts believe it could be that the wet conditions help worms migrate faster, or that the rain causes vibrations that sound like a predator, says Scientific American.



  • What are atmospheric rivers?

    Winds in the lower atmosphere can transport evaporated ocean water around the world, dumping snow and rain along the way. One of these fast-moving streams can carry about 25 times the volume of water that's in the Mississippi, reported National Geographic. "In a way, they're actually the biggest rivers on earth," Marty Ralph, a researcher at the Scripps Institution of Oceanography in La Jolla, Calif., told National Geographic. "They're just in the air instead of on the ground." In spring of 2019, atmospheric rivers caused rain and flooding in Northern California.



  • What is a moonbow?

    Light from the moon can create a rainbow at night if there is enough moisture in the air. Moonbows are seen more often in the tropics, like Hawaii, than at higher altitudes, wrote WGN meteorologist Tom Skilling. If the water droplets are small—like in a mist—it will create a white or gray rainbow called a fogbow, explains



  • What’s the difference between a snow squall and a blizzard?

    A snow squall lasts for about 30 to 60 minutes, dumping snow in a short amount of time. These storms are dangerous because they can reduce visibility quickly, which makes driving hazardous. Blizzards can also make transportation risky because they produce winds of 35 mph or more, which can blow snow on the roads.



  • How can wildfires affect the weather?

    If a wildfire is strong enough, it can create a thunderstorm. This is known as a pyrocumulonimbus cloud, or pyroCb, according to YaleEnvironment360. PyroCbs are happening more often and in new places. This is likely because the globe is getting hotter and creating stronger wildfires. This puts “more vigorous plumes of smoke, black carbon, and water vapor” into the air, said Mike Flannigan, director of the Canadian Partnership for Wildland Fire Science at the University of Alberta, who spoke with YaleEnvironment360.



  • What is an anticyclone?

    High-pressure systems are called anticyclones. They bring sunny skies with few clouds because they produce light wind that blows clockwise.



  • What is a roll cloud?

    These are rare cloud formations shaped like long, horizontal tubes. They are found near a moving cold front when warm, moist air rises and cools, according to NASA. They can look strange because they are entirely separate from the thunderstorm.


  • What is a shelf cloud?

    Also called an arc cloud, these clouds sit in thunderstorms, and mark the boundary between warm air moving up and cold air moving down. Unlike roll clouds, they aren’t detached from their storm system.



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