The Beautiful and Amazing Waterspout

Posted by Steven Goodheart on December 21, 2009 · 7 Comments 

If you’ve visited my other nature blog, Berkeley, Naturally! you know weather is one of my great passions. In my post “Escape from New England-a weather nut’s confession,” I describe how I looked forward to the big summer push of moisture from Baja, Mexico, that gave us our July and August thunderstorms in Las Vegas.

But aside from those summer thunderstorms, weather was pretty boring in Vegas, although the summer heat was fierce. So, as a young boy, I used to read all the books I could on weather. In the heat of summer, I’d go to the Las Vegas library and check out 12 or more books. Then come home, climb in my favorite chair, and read for hours in air-conditioned comfort while the desert heat beat down outside.

The Ethereal Waterspout

In my weather reading, I was always fascinated by the extremes of weather—thunderstorms, tornadoes, blizzards, hurricanes, hail storms—you name it. If it was powerful and exciting, I loved it! And maybe because I lived in the desert, waterspouts were especially fascinating to me. They are so beautiful and so much more ethereal than their more violent brethren, tornadoes.

The Tornadic Waterspout

Some “waterspouts” are simply tornadoes that form or move over water and are thus are called “tornadic waterspouts.” Like any tornado, they form in violent thunderstorms called supercells.   Tornadoes almost always appear in a rotating area of clouds that extends beneath a severe thunderstorm called a wall cloud.  Here’s an example of a tornadic waterspout—a tornado with its associated wall cloud that moved over lake Michigan:

Fair Weather Waterspouts

Fair weather waterspouts, as the name implies, typically form during calm, warm weather along the base of developing cumulus clouds. They start to develop on the surface of the water and then spin their way up into the cloud, whereas a tornadic waterspout, being a tornado, develops downward.

This doesn’t mean a tornado might not first be visible by swirls on the ground; it just means those ground swirls are created by a column of air descending out of the cloud, whether or not the descending column is visible. Fair weather waterspouts are thought to be start as vortexes formed by horizontal wind shear at the water’s surface that spin upward because of the updraft at the face of a developing cumulus clouds or thunderstorms.

Since most waterspouts rotate slower than weakest tornadoes (about 67 mph or less), I wondered what it would be like to sail into one of them with a boat. I imagined it be a little like experiencing a mini-tornado, a little scary but not too dangerous. (There are some reports of fair weather waterspouts with winds well over 100 mph.)

Encounter with a Waterspout

Then I came across a wonderful story of an actual encounter of a ship with a waterspout written by a turn-of-the-century author. It was great account, but I long ago forgot the author’s name. To my delight, I rediscovered the story while researching this article.

The story is called “A Waterspout” and was written by Edward Sylvester Ellis. Here’s an edited excerpt, with all the “good” parts left in:

“The Slavonia, of the Hamburg line left Brunshausen, on the Elbe, on February 26 last, under the command of Capt. H. Schmidt. She had only two passengers. The weather was squally and the air full of mist when she reached the outer Banks, 900 miles from New York, shortly after sunrise on Sunday, March 16.

The big vessel was heading west by north, when, at 7 o’clock, Second Mate Erichsen, who was on the bridge, saw emerge through the mist on the starboard side of the ship, at the distance of about a thousand feet, a towering column which united sea and sky. The column was in front of the ship to starboard, and was moving in a southeasterly direction, apparently at the rate of eight knots an hour…

On rushed the Slavonia, heading west by north: nearer came the waterspout, heading south by east. It soon became evident that the spout could not get by before the Slavonia reached it, and it was now too late to slow up–indeed, a collision was manifestly unavoidable from the start.

[The waterspout] hit the steamer’s bows on the starboard side. A rushing noise accompanied the column, and the water foamed in its wake. Immediately above was a great black cloud from which clouds less dark descended to form a funnel, or inverted cone. The middle of the column was white, apparently because it contained snow.

The column’s narrowest diameter was about twelve feet, while it was three times as broad as its base, which reproduced in water and inverted the cloud-formed funnel above. The whole column rotated with a spiral motion.

The Slavonia shook under the shock caused by contact with the column of water, but kept on her course none the worse for the collision. A few flakes of snow on her bow were the only evidence of the collision after the pillar of water had passed off to port.”

A large ship like the Slavonia would receive little damage from a waterspout, but smaller craft should definitely avoid them. A strong waterspout can easily knock over or swamp a small pleasure boat or sail boat. Waterspouts are also a real danger to aircraft because they are often nearly invisible and carry significant turbulence. Helicopters are especially vulnerable to the rotating winds in a waterspout.

So, where can you see a fair weather waterspout? You’re most likely to see a waterspout in the tropics, given their need for relatively calm, warm, moist air and developing cumulus clouds. People in Florida and the Florida Keys see as many as 400 to 500 a year, but waterspouts are reported in mid-latitude areas as well, such as the Great Lakes and over large bodies of water in Europe.

How Waterspouts Form

If you were watching a waterspout form what would you see? Typically, waterspouts have a five-part life cycle:

Stage 1

If you could watch from the air, the first thing you’d notice was the formation of a dark spot on the water surface. This dark spot is formed by a vortex of air spinning rapidly at the water’s surface, roughing up the water’s surface and making it look darker.

Stage 2

The next thing you’d see would be an expanding light-and-dark spiral pattern on the water’s surface as the vortex grows in strength and begins to pull more surface air in towards the low pressure at the center of the rotation. Invisible to you, the vortex is now being drawn up the side of the neighboring cumulus by the cloud’s updraft.

Stage 3

As the vortex strengthens, and winds neared 40 mph, you would next see a spray ring called the cascade develop as the waterspout whips the water at ever higher speeds. At this point, you’d no longer have to be in the air to see the developing waterspout, but could notice it from a boat.

Stage 4

In the fourth stage, the next thing you’d see would be the formation of the visible condensation funnel. Contrary to popular belief, the tunnel is not made visible by the waterspout sucking huge quantities of sea or lake water up into the funnel. The winds just aren’t strong enough for that. Rather, the low pressure in the tunnel caused the warm, moist air to cool and condense, forming water droplets than can be seen.

As the waterspout reaches maturity, the visible funnel can grow hundreds feet high or stretch all the way from the water to the cloud base. The tallest waterspout on record reached 3,000 feet in length! Once the waterspout reaches the mature stage, it can last a few minutes or over an hour if the conditions are right.

Stage 5

The fifth and final stage is dissipation. Waterspouts typically begin to fall apart as the inflow of warm air into the vortex weakens. This is often caused by rain from the neighboring cumulus falling into the funnel, cooling it. As this happens, the spray vortex weakens, the funnel thins, shortens, and twists and then just fades away.

Some day, a Dream Come True

I hope you found this post interesting and informative. Someday, I hope my childhood dream of seeing a waterspout comes true, and I can be as close as this woman in Florida:

For now, pictures and videos will have to do.

Speaking of videos, if you’d like to see a spectacular movie of a waterspout that formed in Singapore, take a look at this YouTube video. I’m sure you’ll enjoy as much as I did:

http://www.youtube.com/watch?v=3g_Kqowj6rs

♥♥♥

Filed under climate, earth-science, meteorology, weather · Tagged with condensation-funnel, cumulus, Edward-Ellis, fair-weather-waterspout, funnel, supercell, thunderstorm, tornadic-waterspout, tornado, vortex, waterspout, waterspout-formation, wind, wind-speed, wonder