[ti:What Is a 'Bomb Cyclone?'] [by:www.51voa.com] [00:00.00]更多听力请访问51VOA.COM [00:00.88]This is What's Trending Today... [00:04.48]When it comes to weather, it is hard to sound more frightening [00:09.40]than to call a storm a "bomb cyclone." [00:14.48]But that is how weather experts are describing a huge winter storm [00:20.68]that is hitting the U.S. East Coast this week. [00:25.28]From the northern state of Maine to Georgia in the south, [00:32.00]the storm has brought high winds and heavy snow. [00:37.40]Schools and government offices have closed because of the weather [00:43.24]and thousands of flights have been cancelled. [00:48.12]But as fearsome as the storm is, [00:51.52]it probably will not be as "explosive" as the name sounds. [00:59.16]Weather experts, or meteorologists, [01:03.36]have used the term "bomb" for storms for many years. [01:09.84]The word has a clear definition for weather experts, [01:14.28]says University of Oklahoma meteorology professor Jason Furtado. [01:22.48]After "bomb cyclone" appeared in a Washington Post story this week, [01:29.04]the weather term became popular, or "blew up," on social media. [01:36.60]It became a top trending topic. [01:41.04]The same thing happened four years ago with the phrase "polar vortex" [01:48.20]-- another long-used weather term that was not well known to the public. [01:54.72]The technical term is "Bombogenesis." [02:00.44]Bomb cyclone is a shorter way of saying it, [02:04.44]which is better for social media, says meteorologist Ryan Maue. [02:11.32]He helped popularize "polar vortex" in 2014. [02:18.32]Although "bomb cyclone" sounds bad, Maue notes, nothing will actually explode. [02:27.64]Storm strength is measured by central pressure. [02:32.32]The lower the pressure, the stronger it is. [02:36.80]A storm is considered a "bomb" [02:39.88]when the pressure drops quickly -- at least 24 mililbars in 24 hours. [02:49.32]This week's storm in the United States is expected to strengthen [02:55.20]at two times that rate, says Bob Oravec. [03:01.28]He is the lead forecaster at the National Weather Service's [03:05.92]Weather Prediction Center. [03:09.16]Around the world, about 40 to 50 bomb cyclones develop each year. [03:16.72]However, most are over the open ocean and few people notice them. [03:25.00]"We use the term bomb," Furtado said. [03:29.56]"We (weather experts) know what it means, [03:31.40]but I do think it gets a little hyped up." [03:35.57]I'm Mario Ritter. 更多听力请访问51VOA.COM