Why Are Hurricanes and Typhoons More Common in the Pacific?

Typhoon Nepartak swirling over the Pacific Ocean on July 6, 2016
Typhoon Nepartak swirling over the Pacific Ocean on July 6, 2016

 Taiwan endured the impact of ferocious Typhoon Nepartak this month, a storm that crashed ashore with winds equivalent to those of a category four hurricane. The island nation, which sits off the southeastern coast of China, is a regular target for major tropical cyclones, Nepartak being the second such intense storm to come ashore there within the past year. The eastern Pacific Ocean is also hopping this summer, producing one tropical cyclone every couple of days so far this month. Meanwhile, the Atlantic has been dead quiet. This is a common pattern during the summer, and it raises a natural question: Why are hurricanes and typhoons more common in the Pacific Ocean than the Atlantic Ocean?

Tropical cyclones go by many names around the world, and the terminology can get confusing. Once a tropical cyclone strengthens to the point where it has gale-force winds—39 mph or greater—it becomes a tropical storm. A storm that reaches tropical storm strength usually gets its own name to help us quickly identify it in forecasts and warnings.

Once a tropical storm begins producing sustained winds of around 75 mph, we call the storm a typhoon in the western Pacific near Asia and a hurricane in the oceans on either side of North America. A “typhoon” and a “hurricane” are the same kind of storm, they just go by different names.

The Atlantic Ocean sees its fair share of named storms each year, averaging around 11 named storms in a normal season. The eastern Pacific Ocean averages around 16 named storms every year, and the western Pacific churns out more than two dozen named storms in a normal year. There are several factors that contribute to the Pacific teeming with cyclones while the Atlantic can sometimes struggle to see rogue thunderstorms let alone anything more ominous.

THE PACIFIC IS WARMER

Sea surface temperatures (°C) around the world on July 14, 2016. Image credit: NOAA/ESRL/PSD

 
Warm sea surface water is the fuel that drives tropical cyclones. If you ignore large-scale anomalies like El Niño and La Niña, the waters in the Pacific Ocean are usually warmer than those of the Atlantic Ocean, and the temperatures stay pretty toasty through almost the entire year. If you were to take a swim in the water off the coast of the northern Philippines, it would feel like you dunked yourself into a freshly drawn bath, just as it would if you took a dip in the ocean at a beach in Florida. Though parts of the Atlantic get uncomfortably warm, the expanse of hot water is much larger in the Pacific than it is in the Atlantic. The larger pool of steamy water gives more disturbances the opportunity to spin-up into major storms.

The persistent warmth of the western Pacific allows the typhoon season there to last the entire year, unlike around North America where it starts in May in the eastern Pacific and June in the Atlantic, both stretching through November. In addition to ocean currents, which have a major impact on sea surface temperatures, another significant factor in the Atlantic’s relative coolness is its proximity to land.

THE LAND IS A GOOD DEFENSE

Deep cold fronts don’t stop at the beach when they’re finished sweeping across the United States and Canada. Some cold fronts can keep sailing long after they leave shore, traveling across vast swaths of the ocean and dipping as far south as the islands of the Lesser Antilles. The constant train of cold fronts marching out to sea during the early spring and late fall can put the kibosh on tropical cyclone formation, stabilizing and drying out the air and chilling the warm sea surface waters. The Pacific doesn’t have that common issue—most storms stay far enough north that they don’t much affect the typhoon and hurricane seasons across the basin.

Saharan dust crossing the Atlantic Ocean in June 2010. The image was stitched together from a series of images collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite during successive orbits; gray areas show gaps between satellite overpasses. Image credit: NASA Earth Observatory

 
Dry air is also a major problem in the Atlantic Ocean. The Saharan Air Layer (SAL) recently made the news as dust blowing off Africa’s Sahara Desert traveled across the entire ocean and made for some hazy, colorful sunsets in the southeastern United States. These puffs of dry, dusty air coming off Africa don’t only alter our sunsets, but they can have a big effect on tropical cyclones. Dry air is the arch nemesis of tropical cyclones; by their very nature, these cyclones need as much moist air as they can ingest to survive and thrive during their life cycle. Dry air that spirals into the center of a tropical cyclone can collapse the thunderstorms and cause the storm to fizzle out.

Thunderstorms that develop over Africa also serve as the nucleus for some of the worst storms the Atlantic can produce. Disturbances that drift off the African coast can quickly come to life near the Cape Verde Islands, gaining steam as they spiral west toward North America. If western Africa experiences a drought (or the SAL keeps blowing west), it can have a significant impact on the Atlantic hurricane season.

The ironic thing about tropical cyclones is that they produce some of the worst winds on Earth, yet relatively weak winds in the atmosphere can force them to dissipate. Atmospheric wind shear—strong winds that change speed and direction with height—is a death sentence to budding tropical storms. Winds blow the tops off the thunderstorms and prevent them from developing into much more than a brief pulse. Wind shear is also much greater in the tropical Atlantic than it is in the tropical Pacific, both due to regular jet stream patterns and the constant stream of low-pressure systems blowing off North America. 

What's the Difference Between Memorial Day and Veterans Day?

iStock/flySnow
iStock/flySnow

It may not be easy for some people to admit, but certain national holidays often get a little muddled—namely, Memorial Day and Veterans Day. In fact, the U.S. Department of Veterans Affairs sees the confusion often enough that they spelled out the distinction on their website. The two days are held six months apart: Veterans Day is celebrated every November 11, and Memorial Day takes place on the last Monday of May as part of a three-day weekend with parades and plenty of retail sales promotions. You probably realize both are intended to acknowledge the contributions of those who have served in the United States military, but you may not recall the important distinction between the two. So what's the difference?

Veterans Day was originally known as Armistice Day. It was first observed on November 11, 1919, the one-year anniversary of the end of World War I. Congress passed a resolution making it an annual observance in 1926. It became a national holiday in 1938. In 1954, President Dwight D. Eisenhower changed the name from Armistice Day to Veterans Day to recognize veterans of the two world wars. The intention is to celebrate all military veterans, living or dead, who have served the country, with an emphasis on thanking those in our lives who have spent time in uniform.

We also celebrate military veterans on Memorial Day, but the mood is more somber. The occasion is reserved for those who died while serving their country. The day was first observed in the wake of the Civil War, where local communities organized tributes around the gravesites of fallen soldiers. The observation was originally called Decoration Day because the graves were adorned with flowers. It was held May 30 because that date wasn't the anniversary for any battle in particular and all soldiers could be honored. (The date was recognized by northern states, with southern states choosing different days.) After World War I, the day shifted from remembering the fallen in the Civil War to those who had perished in all of America's conflicts. It gradually became known as Memorial Day and was declared a federal holiday and moved to the last Monday in May to organize a three-day weekend beginning in 1971.

The easiest way to think of the two holidays is to consider Veterans Day a time to shake the hand of a veteran who stood up for our freedoms. Memorial Day is a time to remember and honor those who are no longer around to receive your gratitude personally.

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What Is the Kitchen Like on the International Space Station?

iStock/Elen11
iStock/Elen11

Clayton C. Anderson:

The International Space Station (ISS) does not really have a "kitchen" as many of us here on Earth might relate to. But, there is an area called the "galley" which serves the purpose of allowing for food preparation and consumption. I believe the term "galley" comes from the military, and it was used specifically in the space shuttle program. I guess it carried over to the ISS.

The Russian segment had the ONLY galley when I flew in 2007. There was a table for three, and the galley consisted of a water system—allowing us to hydrate our food packages (as needed) with warm (tepid) or hot (extremely) water—and a food warmer. The food warmer designed by the Russians was strictly used for their cans of food (about the size of a can of cat food in America). The U.S. developed a second food warmer (shaped like a briefcase) that we could use to heat the more "flexibly packaged" foodstuffs (packets) sent from America.

Later in the ISS lifetime, a second galley area was provided in the U.S. segment. It is positioned in Node 1 (Unity) and a table is also available there for the astronauts' dining pleasures. Apparently, it was added because of the increasing crew size experienced these days (6), to have more options. During my brief visit to ISS in 2010 (12 days or so) as a Discovery crewmember, I found the mealtimes to be much more segregated than when I spent five months on board. The Russians ate in the Russian segment. The shuttle astronauts ate in the shuttle. The U.S. ISS astronauts ate in Node 1, but often at totally different times. While we did have a combined dinner in Node 1 during STS-131 (with the Expedition 23 crew), this is one of the perceived negatives of the "multiple-galley" scenario. My long duration stint on ISS was highlighted by the fact that Fyodor Yurchikhin, Oleg Kotov, and I had every single meal together. The fellowship we—or at least I—experienced during those meals is something I will never, ever forget. We laughed, we argued, we celebrated, we mourned …, all around our zero-gravity "dinner table." Awesome stuff!

This post originally appeared on Quora. Click here to view.

Clayton "Astro Clay" Anderson is an astronaut, motivational speaker, author, and STEAM education advocate.

His award-winning book The Ordinary Spaceman, Astronaut Edition Fisher Space Pen, and new children's books A is for Astronaut; Blasting Through the Alphabet and It's a Question of Space: An Ordinary Astronaut's Answers to Sometimes Extraordinary Questions are available at www.AstroClay.com. For speaking events www.AstronautClayAnderson.com. Follow @Astro_Clay #WeBelieveInAstronauts

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