9 February 2019, Blog No. 3
Every once in a while, you hear a short phrase that is clever, concise, practical, and can even rhyme for bonus points. With being involved in the field of/learning about meteorology for over a decade, I have heard quite a few of these phrases that are nifty little guideposts for remembering various aspects of the weather. This blog is the first in a series of some "weather wisdoms" that I will share with you in the future.
My memory fails me when trying to recall where exactly I heard this phrase, but it has stuck with me ever since. This short rhyme describes a rule of thumb for how to remember the range of temperatures between Fahrenheit and Celsius.
Starting with “30s are hot,” 30°C is equivalent to 86°F, which most would consider hot. Our mean high temperature in late June and also in mid to late August is around 86°F. Onward to “20s are pleasing,” 20°C is equivalent to 68°F, recognized as standard room temperature and comfortable to most people. Any temperature slightly below or above 20°C would fall in the mid 60s to upper 70s in Fahrenheit, so this is a range that most people are relatively happy with. Now we are down to “10s are not,” where 10°C is equivalent to 50°F. While this temperature may not necessarily be cold to most persons, this is the point where most people would likely elect to stay inside rather than spend time outdoors. A few ticks down the scale to 7°C or 8°C to the mid 40s and temperatures certainly become less pleasing. And finally, to tie it all together, “0 is freezing,” is the perhaps the most famous conversion known to humankind: 0°C is 32°F, the temperature at which liquid water freezes. So, there you have it! The next time you are trying to ballpark temperatures for the Celsius scale, remember this short phrase for guidance.
Again, these are just the first five weather wisdoms that come to mind, and I plan on sharing many more of these in the future. If you have heard of any, feel free to send them along on Facebook, Twitter, or via email to firstname.lastname@example.org.
Mohee, F. M., & Miller, C. (2010). Climatology of Thunderstorms for North Dakota, 2002–06. Journal of Applied Meteorology and Climatology, 49(9),
Figure 1. "Red sky in morning" taken by me at approximately 7:10 AM EDT on 10 October 2018 in Johnston County, NC. Hurricane Michael, or what would be left of it, was approaching from the southwest.
You have probably heard this one before, but may not be familiar with the reasoning that gives it meaning. This webpage1 from the Science Reference Services at the Library of Congress gives a concise overview of the meaning of the old weather proverb, but I will attempt to break it down in the following paragraph.
When we have our most brilliant sunsets or sunrises, clouds are typically a significant part of the magnificent visual the atmosphere provides. The ragged edges and odd shapes that clouds create in concert with the various angles of the diffused sunlight that hit the cloud droplets reflect a plethora of reds, oranges, yellows, pinks, purples, and sometimes even other hues. Now, if we include the time of day we are seeing these colors, we can make some very generalized assumptions about the short-term (within 12 hours) weather changes coming our way.
In the contiguous United States (the lower 48 states), weather usually moves from west to east due to the way that Earth’s climate system exists. In addition, the Sun rises in the east and sets in the west. So, if a large number or swath of thick clouds are rolling in from the west and we see the beautiful red sky/sunrise in the morning, that adverse weather is likely on its way toward us over the next several hours. Conversely, if you are treated to a gorgeous sunset, the those clouds associated with the weather system should be on the way out.
Take these two examples from my own experience when I saw a prime example of a “red sky in morning” when Hurricane Michael was approaching from the southwest on October 10, 2018 (Fig. 1) and also when I experienced one of the greatest sunsets I have ever witnessed back in October 2016 (Fig. 2) when clear, calm weather occurred the next day.
This one is self-explanatory. Symmetry is typically not a natural occurrence, so when it does occur in nature it forebodes likely intense or high-impact weather. For example, a symmetrical tropical cyclone such as Hurricane Michael last year in October 2018 (Fig. 3) is indicative of a system with healthy inflow and outflow, and is a self-perpetuating entity capable of causing a lot of damage over vast areas in minimal amounts of time.
Attending to the “prettier it looks,” part of the statement, a lot of weather can be quite beautiful and visually appealing, but that can be a telltale sign of how healthy or powerful a storm can be. Take the well-formed cumulonimbus cloud in (Fig. 4) which looks really cool, but marks a strong thunderstorm with several dangers including far-reaching lightning outside of the cloud. So, if you are ever caught outdoors, steer clear of the coolest looking clouds, and if you are perhaps estimating the strength of a weather event using technology or in the field, see if it passes the eye test -- if it looks impressive, it likely is impressively intense.
Go back in time and recall the worst thunderstorm you can remember. Perhaps the rain was relentless, hail pounded the perimeter of your place of dwelling, and near-constant lighting and thunder had you gripping your fists extra tight. I bet that storm was over just as quick as it began. Although time is relative (thanks Einstein!) and it may have seemed like ages that the storm raged on, but some suggest a correlation does exist between forward storm speed and the severity of the storm. However, Mohee and Miller (2010)4 concluded that the opposite was true (the slower moving storms were more intense) after conducting a five year climatology of thunderstorms in North Dakota (p. 1887).
That is to say, a general rule of thumb is that the stronger the storm/weather system, the faster it will approach and the quicker it will be over. However, we will always see exceptions to this rule, such as the slow-moving Hurricane Florence of 2018 or strong thunderstorms that park it over one location and dump loads of rain in the summertime due to lack of steering in the upper troposphere. So, taken with a grain of salt, the statement does have validity in that the more potent the storm, the more rapidly the system is likely moving.
Meteorology is a young science. Whereas people have used natural signs and old wives’ tales to predict and understand weather for centuries, the actual sound-science analysis and research into meteorology only began in the early 20th century. Thus, we understand a large proportion of atmospheric science, but the discipline is certainly not as advanced as mathematics of physics.
As a consequence of meteorology being one of the new kids on the block, some days still come along that result in the complete opposite of the forecast, catch scores of people off guard, or leave extreme weather-lovers disappointed at the end of the day. This statement rings true especially in terms of severe weather, when all ingredients are in place, but the atmosphere just never produces any lifting mechanisms or nothing sparks any impactful weather. And of course, on the other hand, we can get a surprise snow flurry or rain shower from a basic, run-of-the-mill air mass that decides to surprise meteorologists and go against the forecast.
Figure 2. "Red sky at night" captured by me at sunset on 3 October 2018 on the campus of NC State University just west of Raleigh, NC. The air was clear and crisp, and the next day brought beautiful Carolina blue skies and brought brisk, fall-time conditions.
Figure 3. An intense Category 4 Hurricane Michael approaching a Florida panhandle landfall on 10 October 2018. Captured from GOES-East satellite with GeoColor. Photo from NOAA2
Figure 4. Photo of a towering cumulonimbus cloud with a far-reaching anvil at the top of the cloud, indicative of a mature thunderstorm likely causing severe weather at the surface. Photo from ThoughtCo3