In the year 350 B.C., the Greek philosopher Aristotle gave one of the earliest descriptions of weather patterns in a text called Meteorologica. It included some of mankind’s first attempts to observe and record natural phenomena like water evaporation and earthquakes. Although it was a far cry from the Weather Channel, Meteorologica was the start of something that had eluded human beings for time immemorial: the ability to understand—and even predict—the weather.
Modern weather forecasting is a $7 billion-a-year industry—and for good reason. Despite all the advanced technology of modern society, humans are still pretty much at the mercy of the elements. America’s GDP can fluctuate by more than $1.34 trillion depending on the weather. In 2020 alone, more than 60,000 weather events killed 585 people in the United States and injured more than 1,700 more with flash floods, tropical storms, heat, tornadoes, ice storms, and thunderstorms doing most of the damage.
Weather forecasters are easy targets because, like football referees, people tend to take notice only when they get it wrong. The reality, however, is that meteorologists are right in astonishing percentages. When weathermen and women issue seven-day forecasts, they’re accurate about 80 percent of the time—90 percent for five-day forecasts.
If someone had told Aristotle that human beings would one day be able to accurately predict the weather nine times out of 10, five days in advance, he likely would have laughed at their overactive imagination.
It’s important to note that climate and weather are not interchangeable terms. Weather describes the short-term—day-to-day and hour-to-hour—state of the atmosphere including temperature, precipitation, wind, and visibility. Climate, on the other hand, measures average weather patterns over several decades.
I used a variety of scientific sources to compile this list of common weather terms that RVers should know and understand.
Humans inhabit the very bottom of the Earth’s atmosphere and everything above creates atmospheric pressure. High-pressure systems form when downward pressure creates a clockwise air rotation, unlike low-pressure systems which generate counter-clockwise rotation. Both phenomena which are measured with barometers are critical to predicting weather events.
Vehicle accidents are the leading cause of winter-related fatalities so when a meteorologist warns about the potential for black ice drivers should take it seriously. Black ice gets its name because it’s so thin that it’s nearly invisible on the road surface but the ice itself isn’t black. Black ice forms when sudden temperature increases causing snow to melt and drip onto roadways that are still cold enough to make the liquid water freeze on contact.
Not just any big snowstorm qualifies as a blizzard. A storm must meet three criteria to earn the harshest classification in winter weather. Blizzards have frequent wind gusts of at least 35 mph, sustained falling or blowing snow that reduces visibility to less than a quarter-mile, and these conditions are maintained for at least three consecutive hours.
Breezy and windy
The terms windy and breezy are sometimes used interchangeably but they don’t describe the same phenomenon. Breezy conditions involve air moving between 12 and 22 mph during pleasant conditions. Windy days, on the other hand, involve stronger winds up to 50 mph during stormy or inclement weather.
The dew point represents the temperature to which air would have to be cooled to reach a level of moisture saturation. When it reaches the dew point, droplets of water or dew begin to form on solid objects like grass and vehicles.
Most people know droughts result from an extended lack of precipitation and abnormally high temperatures but overpopulation and land overuse are contributing factors, too. Droughts are among the most destructive forces in nature—only hurricanes are more economically damaging to the United States.
The opposing warm half of ENSO is called El Niño (The Boy) which occurs irregularly every two to seven years and is often followed closely by a La Niña (see below) pattern. It warms the oceans and creates the opposite effect in terms of not just ocean temperatures but atmospheric pressure. It, too, is associated with irregular and sometimes severe weather patterns.
Flash flooding occurs when large amounts of water from sudden torrential rains—or occasionally an incident like the breaking of a dam—gushes through a narrow area that isn’t capable of absorbing high volumes of water. In many cases, flash floods which can roll cars and destroy houses happen in the immediate aftermath of extended droughts where parched land can’t absorb the influx of water quickly enough.
Flooding is one of the deadliest and most destructive weather phenomena in the country and on the planet. Weather professionals use specific terminology to describe rivers as they rise from excess water. A flood crest is the peak—the highest level the water will rise—which is the most significant and dangerous time of a flood but also an indication that the flood will soon recede.
Freezing rain is formed through the same general process that creates sleet (see below) but they’re not the same thing. Sleet falls to the ground as ice. Freezing rain, on the other hand, remains in liquid form until it hits a cold object and then instantly freezes on contact.
Gardeners make their plans according to the first and last frost schedules in their respective agricultural zones. The frozen version of dew, frost occurs when cold, moisture-soaked air deposits water that freezes and leaves an icy film on things like plants and car windows.
Unlike sleet (see below) which is ice formed by rain falling through very cold air, hail is a much more dangerous phenomenon associated with much more dangerous weather. Hail forms when powerful updrafts inside of thunderstorms force water well above the freezing level. That water freezes into large hailstones which eventually become too heavy for the updraft and come crashing down to Earth.
The dreaded three H’s are hazy, hot, and humid. Hot is self-explanatory, humidity deals with the level of moisture in the air but what exactly does it mean to be hazy? A haze can look like a thin fog but it isn’t caused by precipitation. Hazy conditions occur when large amounts of fine, dry particulate matter like dirt are suspended in the air which scatters light and gives the lower atmosphere a cloudy appearance.
The heat index is essentially the same thing as the wind chill factor (see below) but for the opposite sensation of environmental exposure. It represents how hot the temperature feels when humidity is considered. The more humid the air, the less perspiration can evaporate which cripples the human body’s cooling system and makes it feel hotter when it’s humid outside.
Heat waves are long periods of abnormally warm weather. To qualify as a heat wave, it must last for at least two days and consist of temperatures that are outside the region’s historical average.
Ice storms are extended episodes of freezing rain that occur when precipitation falls in liquid form and freezes on contact. It becomes an ice storm when a quarter-inch or more of ice accumulates creating dangerous conditions. Ice storms which can be deadly and cause a lasting impact can add 500 pounds to the weight of power lines and increase the weight of tree limbs by a multiplier of 30.
Jet streams are thin but intense winds in the highest reaches of the atmosphere. Following the boundaries of cold and warm air, jet streams blow west to east although their flow sometimes shifts to north and south. Not only do these rivers of air affect global weather and help meteorologists identify atmospheric patterns but they’re crucial to air travel as flying into and out of them can dramatically affect fuel consumption and flight time.
One half of the El Nino-Southern Oscillation (ENSO) phenomenon, La Niña (The Girl) is a global weather pattern that describes a dramatic cooling of ocean temperatures in the Western Hemisphere. La Niña is known for its disruptive impact on weather specifically heavy rainfall and an increase in low-pressure systems.
Microbursts are among the most dangerous and unpredictable weather phenomena on Earth and they form inside of already-dangerous thunderstorms. Updrafts—columns of rapidly rising air—sometimes suspend large amounts of rain and ice and when the updraft weakens, there’s nothing left to hold all that water and ice in place. That leads to a massive downdraft which sends the core of the column crashing to the ground and, upon impact, bursting out in all directions, leading to tornado-like winds, pressure, and destruction.
Nor’easters are major, dangerous storms that are exclusive to the Northeastern United States. Geography, however, is not where these storms get their name. Nor’easters are named for the direction in which the storm’s most intense winds blow. Those winds are usually severe and they’re known to bring rain and snow and cause flooding and storm surges.
The menacing phrase polar vortex is a relatively new term for winter weather forecasting but meteorologists have understood it as a concept for decades. A polar vortex occurs when a large section of very cold air, usually the coldest in the entire northern hemisphere, is pushed down the North American continent as far south as the Midwestern and Northeastern United States.
Relative humidity is closely related to dew point (see above) but the two terms are not interchangeable. This term describes the amount of atmospheric moisture that exists relative to the amount that would exist if the air was saturated.
There are garden-variety thunderstorms and severe thunderstorms and when meteorologists mention the latter, the public should take it seriously. To be classified as severe, thunderstorms must include two potentially deadly elements: winds of at least 58 mph and hail at least one inch in diameter.
One of the more unpleasant precipitation events associated with winter is sleet which stings the skin and turns roads and sidewalks into ice-skating rinks. Sleet graces the world with its presence when rain or melted snow freezes and turns into ice on its way from the sky to the ground.
It’s common to hear meteorologists warn that storm surge is one of the deadliest and most dangerous parts of major weather events like hurricanes. The phenomenon occurs when significant storms cause an abnormal rise in seawater above the limits of the astronomical tide. Storm surges can cause rapid, significant, and deadly flooding in coastal regions.
Before a weather event graduates into a tropical storm, it’s a tropical depression. The infant stage of a hurricane, a tropical depression is a tropical cyclone with maximum sustained winds up to 38 mph.
People sometimes use the terms tropical storm and hurricane interchangeably but one is an evolution of the other. Tropical storms form in the same places and under the same conditions as hurricanes but they achieve maximum sustained wind of just 39–73 mph. If a tropical storm’s maximum sustained winds hit 74 mph, it becomes a hurricane.
Watches and warnings
Meteorologists issue precautions to inform residents about the likelihood of serious and fast-moving weather events like tornadoes and severe thunderstorms. Watches are less serious and indicate that conditions are present for the formation of a severe weather event. Warnings, on the other hand, indicate that an event has been identified by a person or radar, a tornado or thunderstorm is imminent and to seek shelter immediately.
Everyone in North America north of a certain latitude knows there are two temperatures they have to consider when getting dressed in the morning in winter—the actual temperature reading and the one that counts: the wind chill factor. Also known as the feels-like temperature, wind chill represents how cold the weather feels on human skin when the chilling effect of the wind is taken into consideration.
Two words cold-weather commuters never want to hear are a wintry mix. When precipitation travels through an above-freezing warm layer of air followed by a cold, below-freezing layer, snow, sleet, and freezing rain can fall simultaneously.
Since we’re talking weather, here are a few related articles:
- Are You Prepared for the Next Great Weather Event?
- Lightning and Thunderstorms: Safety Tips for RVers
- How Safe is an RV in a Lightning Storm?
- Severe Weather: Tornado Safety Tips for RVers
- As Hurricane Season Ramps Up It Is Never Too Early to Prepare
- 5 Tips for Avoiding Extreme Weather While RVing
- Dust Storms and Haboobs: Safety Tips for RVers
- What’s in Your RV Emergency Kit?
In the spring, I have counted 136 different kinds of weather inside of 24 hours.
—Mark Twain (1835-1910)