Archive for category Weather
How to run your A/C to beat the heat—not your wallet
For weeks now, we Minnesotans have dodged the severe heat hitting other areas of the USA and Europe. But now we are sweating out a prolonged spell of high temps that may hit 100 degrees Fahrenheit tomorrow.
Fortunately, our home is well shaded, which makes it practical to wait until well into the day before turning on our air conditioner. Once the inside gets to a steamy 78, I set the temperature to 74, which takes out the humidity and thus provides a comfortable environment for my wife and grandkids that we watch over during the work week. Our bedrooms are on the second floor, where temps run a few degrees higher, so for a good sleep, I reduce the A/C to 72.
My strategy for cooling involved a lot of trial and error—my wife being the barometer, letting me know in no uncertain terms when I’m being too miserly about running the A/C. However, what do scientists suggest based on actual data? The New York Times recently provided a Wirecutter report that presents a counterintuitive suggestion that It’s Actually Okay to Run the AC All Day (Even If You’re Not Home). This recommendation stems from studies by Thom Dunn, who compared electrical use in two similar apartments within the same building. He applied a strategy that differed from mine—turning the A/C off at noon and back on again at 5 pm. However, in every case, running the units continuously used less electricity.
I work from home for the most part, and my wife provides daycare, which limits our options on reducing the use of our A/C. However, many people are off to an office on workdays. In that case, per a team of engineers who used energy models that simulate heat transfer and A/C system performance, it pays to program an 8-hour temperature ‘setback.’ Check out the details in this July 2023 report from PBS News.
Stay cool while not sweating the costs by applying a smart strategy for running your air conditioning!
Temperature combines badly with humidity to maximize misery
The Twin Cities tied its record high temperature yesterday at 97 degrees Fahrenheit. However, the winds blew strong with air at a dew point in the low 60s, which made the heat relatively tolerable. After spending most of August at our second home in southwest Florida (leaving there just as Hurricane Idalia hit), my wife and I got acclimated to a far more uncomfortable daily combination of heat and humidity.
Before departing for Minnesota, I set up a SensorPush to monitor temperature, humidity and dew point—the temperature at which air becomes saturated with water vapor. I want to be on guard for the air conditioning going out. If that happens in Florida homes, mold can grow. After experiencing this once (due to renters not running the A/C) and dealing with an expensive remediation, I am keen to prevent another episode.
Closely related to dew point is the wet-bulb temperature, which, as chemical engineer, I learned how to measure with a sling psychrometer. The wet-bulb-temperature can then be converted to relative humidity.
To prevent heat-related deaths in training camps, the US military developed a more sophisticated measure called the wet bulb globe temperature (WBGT). It provides a good measure for the advisability of being active in full sun. The Texas University Interscholastic League requires that outdoor practices be shut down if WGBT exceeds 92.
“As with all indices that integrate elements of the thermal environment, interpretation of the observed levels of WBGT requires careful evaluation of people’s activity, clothing, and many other factors, all of which can introduce large errors into any predictions of adverse effects.”
– Grahame M Budd, Wet-bulb globe temperature (WBGT)–its history and its limitations
Other measures use to gauge comfort are Heat Index and Feels Like Temperature (FLT). I like the FLT because it accounts for the benefits of evaporative cooling. For example, as I write this, the actual temperature is 95 degrees and the FLT is only slightly higher at 96.
I’m getting too hot and bothered with all these measurements to continue much longer, but here’s yet another approach used by AccuWeather—the RealFeel Temperature.
What really matters is how you feel and what can be done to avoid discomfort. For example, earlier this summer I went to our Minnesota’s Washington County Fair on a very hot day and stopped in at a beer garden for a cold brew. However, I soon realized that its hot tin roof radiated heat down to the picnic tables—overcoming any advantage to being in the shade.
Sometimes you can find no relief other than hunkering down in an air-conditioned area. How did we ever get by without it?
Hurricane season off to a hot start with great uncertainty ahead
Posted by mark in Nature, Uncategorized, Weather on June 30, 2023
After narrowly dodging Ian’s devastating blow last fall—predicted the day before landfall to hit just a few blocks from my southwest Florida winter home, I am keeping a close watch on this year’s storms.
Just prior to 2024 season on June 1, the National Oceanic and Atmospheric Administration (NOAA) predicted it would be near normal. The NOAA forecasters figure on the winds from the Pacific’s El Nino counteracting the storm inducing temperatures in the Atlantic.
A clash of the titans lies ahead as developing El Niño and notable warmth in the Tropical Atlantic go toe-to-toe.
Ryan Truchelut—the Weather Tiger’s Atlantic Hurricane Season Outlook for May 2023
The Weather Tiger (quoted above) calculated Florida landfall odds this year at slightly above 50/50 for at least 1 hurricane. That was before Tropical Storm Cindy formed behind Tropical Storm Bret in June, creating the first case of two storms in the tropical Atlantic in June since record keeping began in 1851–an alarmingly aggressive start to the season.
Based on these forecasts and the history of USA hurricanes, it seems certain to me that, before 2023 is over, our home will come into harm’s way. Therefore, I keep a close watch on NOAA’s graphical forecasts that display cones showing the probable track of the center of every tropical cyclone. These cones create a great deal of consternation and confusion due to difficulties comprehending probabilities, overly high expectations in the accuracy and precision of forecasting models, and other issues.
While admiring the continuing advancements in meteorology, including this year’s extension to 7 days for hurricane forecasts, I believe (but only half seriously) that if a weather forecast one-day ahead puts me at the bullseye of an oncoming storm, then it will be a miss. This worked for Hurricane Ian. But to hedge my bets, I greatly reinforced our home over the winter to resist wind, rain and flooding—bringing it all up to current hurricane codes and beyond.
Best be safe!