Garrett McNamara riding a big wave at Avalanche, off the coast of Oahu, Hawaii.
May 15, 2012, Ormond Beach, Florida. Photo by
Oct. 2, 2012 --
NASA's Global Precipitation Measurement satellite mission is working to understanding extreme weather with photos of rain and snow worldwide every three hours. But how do these storms look on the ground? NASA's GPM extreme weather photo contest highlights the beauty and ferocity seen first hand from storm-chasers before they duck for cover. Here are NASA's top five picks from over 100 submissions. This photo by Jason Weingart, a photography student at the University of Central Florida, shows a Volusia County lifeguard signaling to surfers at Ormond Beach, Fla., that it is time to exit the water. "The storm actually pushed back on shore as it moved south, and then became strong enough for tornado warnings on three separate occasions. I saw a large wall cloud, another spectacular shelf cloud, and some very tight rotation in the couple hours I stuck with the storm after I left the beach in Ormond," wrote Weingart. NASA Fun Fact: "A shelf cloud is a type of arcus cloud with a wedge shape. It is a low level, horizontal cloud formation usually associated with the leading edge of thunderstorms. The leading (outer) part of the shelf cloud appears smooth due to rising cloud motions, while the underside often appears jagged and wind-torn."
May 22, 2011 Dane County, Wisconsin. Photo by
Atmospheric scientist Grant Petty of the University of Wisconsin - Madison, was with a photography club on a farm in Dane County when he saw this thunderstorm building several miles to the east. "The storm cell dropped 1-3/4 inch hail near Sun Prairie. Fall streaks barely visible under the right side of the anvil may in fact be the falling hail,” he said.
PHOTOS: Sun Dogs, Halos, and Double Rainbows
July 5, 2011 Maricopa, Arizona. Photo by Megg
“This photo was taken in a wash that runs through my neighborhood in Maricopa, AZ. The wash runs north/south through the neighborhood and the haboob (type of intense dust storm) was rolling in from the east," reported photographer Meggan Wood. "I saw the wall of dust coming and quickly drove to the wash to get a good wide-open view of the height of the dust looming over the houses. I barely had time to get back to my car before it hit and I was engulfed! The darkness was surprising but it only lasted about 10-15 minutes before it thinned out enough to where I could drive back home, only about 2 minutes away. This was the giant haboob that made national news when it rolled through and entirely covered all of Phoenix and some surrounding cities. Maricopa is about a half-hour drive south of the Phoenix Sky Harbor airport."
PHOTOS: After the Dust Settles
September 1, 2012 Arlington, Virginia, lookin
Journalist Brian Allen with the Voice of America was at home in Arlington, Va., when this storm rolled over Washington. "The storm that blew through started off with an incredible amount of lightning and then dumped a significant amount of rain in a short amount of time -- on the other side of the river. DC got drenched and Arlington didn't see a drop,” he reported.
NEWS: Lightning Still Largely a Mystery
May 30, 2012 Kechi, Kansas. Photo by Brian Jo
Writer and photographer Brian Johnson is a also an avid storm-chaser for several Kansas radio stations. “As a large squall line moved through the area. The National Weather Service had warned about a large scale Derecho forming and moving through," he wrote. "This spawned a couple brief severe thunderstorms that dumped hail on rush hour traffic before the main line moved in. As the bigger storm moved into the Wichita area, reports were coming in of 70 mph winds and hail. There is an open farm field roughly two miles from my house that I shot lightning on the previous night. I sat there for about 20 minutes before this large squall line pushed through the clouds. I was hit with a pretty good gust front as it got closer, but as the winds increased, I decided to get to shelter. This photo was one of the last ones I took." Read more about Johnson's storm-chasing adventure here:
NEWS: Photos Catch Monster Storm's Approach: Big Pics
PHOTOS: Twilight: 15 Reasons to Watch
As anyone knows, it's easy to make waves. But a lot more than sloshing in the tub goes into the making of the sort of 100-plus-foot (30.5 meter) wave that surfer Garrett McNamara rode on Jan. 28, in Nazaré, Portugal.
For one thing, bathtub waves are essentially micro-tsunamis – very different beasts than the wind waves surfers ride. Tsunamis are created by a pulse of energy, like a sudden rupture in the Earth's crust, a landslide, glacier calving or even a large meteor impact. Their size depends on the size of the pulse. The sky is literally the limit.
Wind waves, on the other hand, are grown. They can be seen forming on any pond when there is a breeze. Add more wind, time and a longer expanse of water, called fetch, and you get larger waves, explained Hendrik Tolman chief of Marine Modeling and Analysis for the National Atmospheric and Oceanic Administration (NOAA). Tolman is also the man who leads the development of the WAVEWATCH III™ forecasting model, which is the same model used by commercial surf forecasters like Surfline.
“Theoretically, with hurricane force winds you could get waves much, much higher” than 100 feet, said Tolman. The largest ocean wind waves recorded are between 120 and 130 feet, and have have been detected by automated buoys inside monster storms. But in that environment, waves are all mixed up and a mess – impossible to ride on a surfboard. Instead, the big surfing waves are found hundreds of miles from the storm where waves have had a chance to get sorted out into neat swells, Hendrik said.
Surprisingly, the best storms for generating these large waves are not necessarily hurricanes. Despite their powerful winds, hurricanes tend to be compact, and so they blow across smaller patches of ocean. It's the broader winter storms, like that which generated the waves in Portugal, that are the giant makers, said Hendrik. The reason is that they blow over larger fetches and blow longer.
“For any constant wind speed, wave growth is limited by the time that this constant wind blows over a given area,” said Scott Stripling a wave and wind forecaster for NOAA in Miami. “Longer fetch lengths yield larger waves.”
That said, wave forecasters have discovered that even some lower-power hurricanes, like Sandy, can make very large swells if they develop something called “trapped fetch waves” that last for more than 18 hours.
“When Atlantic hurricanes make the turn and go up the East coast of the US, they travel in a straight line,” explained Stripling. On the right side of such storms the winds are blowing north, in the same direction the storm is moving. If the storm's speed syncs with the waves it's generating and they are all traveling in the same direction, the winds just keep growing the same waves bigger and bigger as the storm moves up the coast.
“It was the Canadians who noticed it first, when they were being pounded by incredibly big waves that were way larger than expected,” said Stripling.
The final part of the recipe for giant surfing waves is the place where the waves break. The geometry of the sea bottom and coast can focus the waves, making them taller as well as shaping how they break. This is why there are certain places famous for their giant waves – when the swells are there. Places like Nazaré, Mavericks and Cortes banks in California, Jaws in Maui, and many other big wave sites worldwide are watched religiously by surfers and Surfline, so that the world's big wave surfers, like Garret McNamara, can hop on planes and arrive in time to catch the largest waves, which may only last a few hours.