Amusing Monday: Words cannot dampen the essence of rain and snow

After I woke up one morning last week, I noticed that there was a thin layer of water coating the outdoor furniture and concrete around our house. I stepped outside and felt a fine mist in the air. I wondered, could this be the “scattered showers” that weather forecasters had talked about?

Surely, a “mist” is different from “showers,” which is also different from “rain.” But where does one end and another begin according to the experts? A little help from the glossary of the American Meteorological Society revealed that the proper term for a very light precipitation is “drizzle.”

My curiosity got the better of me, and I found myself going deeper and deeper into the terminology for precipitation, both official and unofficial, first in English and then in other languages.

Starting with the lightest precipitation, we have fog, which is not really precipitation, because the condensed water vapor is not falling. The same goes for mist, which consists of water droplets too fine to fall, so they drift about suspended in the air. To qualify as mist, the visibility must be greater than 1 kilometer, or 5/8 mile. Less than that is fog.

With drizzle, the water droplets are small — less than 0.5 millimeters (0.02 inches) — and they may appear to float on air currents, but they eventually fall to the ground. Mizzle, also known as Scotch mist, is a “combination of thick mist and heavy drizzle occurring frequently in Scotland and in parts of England,” according to the AMS glossary. Scotland also gives us Haar, a “cold mist coming from the ocean to the east of Scotland or England.”

Rain comes into play when the droplets are larger than 0.5 millimeter. The intensity of rain is defined as light rainfall when accumulation is no more than 0.10 inch per hour and never more than 0.01 inch in six minutes. Moderate rainfall is between 0.11 and 0.30 inch per hour and never more than 0.03 inch in six minutes. Heavy rainfall is more than 0.30 inch per hour or 0.30 inch in six minutes.

Showers, which have always had me confused, are derived from a cumuliform (vertical-forming) cloud and characterized by sudden onset and ending, usually with large droplets and accompanied by a rapid change in sky conditions. We can have rain showers, snow showers and sleet showers. There are also sprinkles, when the showers are light.

That brings us to the category of frozen precipitation. Freezing drizzle consists of tiny droplets that fall as liquid but freeze upon impact to form a frozen glaze. Freezing rain is basically the same with larger drops, while freezing fog forms the glaze when it comes into contact with exposed objects. The temperature of the water droplets for all three types is generally below freezing, so ice forms the instant they hit a surface. Again, fog is not really precipitation, but there is such a thing as ice fog, which occurs when the condensation freezes and hangs in midair.

When objects on the ground are cooler than the air but not below freezing, we get dew. When objects on the ground are cooler than the air and below freezing, we get frost. Like fog, these are not precipitation.

A snowflake forms when a multitude of ice crystals come together. When snowflakes grow heavy enough, they fall to the ground as snow. If they melt on the way down, we get rain. Sleet, which is frozen rain, forms when snow refreezes or when rain freezes on its way down. Graupel, an official term in the glossary, consists of snow particles surrounded by ice. Often called snow pellets, graupel is smaller than hail.

Hail is basically ice balls between 5 and 50 millimeters (0.2 to 2 inches) across, usually forming when the wind keeps the ice balls aloft to take on more and more moisture.

Besides all the types of precipitation, meteorologists have definitions for precipitation events. Besides showers, we have storms, in which winds rise to between 56 and 63 knots (64 to 72 mph). Snow flurries are technically snow showers, especially when snows are light and brief. Blizzards are at the opposite end of the spectrum, with heavy snow, low temperatures and strong winds.

Some events don’t fall within the standard definitions. “Cloudburst” and “downpour” are unofficial terms for heavy rain. A deluge generally refers to flooding, but it can mean an extended downpour. “Virga” is an official term, meaning precipitation that falls from a cloud, often in streaks, but evaporating before reaching the ground. A squall is a strong and sudden onset of wind, so a rain squall includes the element of rain.

A monsoon is a seasonal wind persisting in one direction. I thought it had something to do with rain, but that is only a recent interpretation. “Monsoon” is from the Arabic word “mausim,” meaning season. It was first applied to the winds over the Arabian Sea, blowing six months from the northeast and six months from the southwest. The word has become popular throughout the world, and monsoons in India are well known for their heavy rains.

I was amused by the ongoing debate over the word “thundershower.” For example, one TV viewer in Cleveland took local meteorologist Mark Johnson to task for using the term while talking about the weather on TV station WEWS, the local ABC affiliate.

“What meteorology school did Mark Johnson go to?” the viewer demanded to know. “The one in the bottom of a Cracker Jacks box???? WHAT in the world is a THUNDERSHOWER…? Is he insane, because he certainly is not funny. Annoying would be a more fitting description…. Time to teach the ole man some new, technically-correct terminology or just replace him altogether with someone who knows how to speak properly. Thank you.”

Mark Johnson took the comment in stride, saying he rarely uses the term — which does not officially exist — but he tries to connect with viewers who may invision “thunderstorm” as something severe.

“Technically,” he said, “every rumble of thunder is logged as a TRW, a thunderstorm. But who am I forecasting for? Other scientists or the general public? Is a light rain shower with a brief rumble of thunder really a storm to you? Probably not.

“Broadcast meteorology is about taking information that can be very technical, and changing it into language and images that viewers can more readily understand and, more importantly, use to plan their daily lives,” he added.

Personally, I see nothing wrong with thundershower, which conveys thoughts of a smattering of lighting and thunder amidst a moderate downpour. Officially, a thunderstorm is a local storm from a cumulonimbus cloud with lightning and thunder, usually with strong winds and heavy rain or hail. After all, the AMS glossary recognizes thundersnow, which is simply snow at the surface accompanied by lightning and thunder in the sky. It seems that the glossary simply needs a new definition for thundershower.

By the way, there is a great article in Grist magazine about new words coming about from the increasing number of extreme weather events. We now have “heat dome,” a huge high-pressure system that traps hot air; “rain bombs,” which are extreme downpours officially called wet microbursts (first video on this page); and “corn sweat,” a humid condition caused by planting lots of corn.

The Dutch have some interesting words for different kinds of weather, as described in “Dutch Review” magazine. Rory, a self-described “Irish guy,” provides us an interesting perspective on Irish weather in the second video on this page.

The third video provides an interesting perspective on the weather from Quark, the extra-terrestrial Ferengi character from “Star Trek: Deep Space Nine.”

The final video is from a list of 119 songs about rain posted by Flourish Anyway, with videos for most of those high on the list.

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