• Fred Gossage

Summer Has Arrived: Beat the Heat!

The start of June also marked the start of meteorological summer, and astronomical summer starts in just a couple of weeks. The weather across our region will get increasingly warmer through the next few months, and as we know, summer in the Tennessee Valley can be downright hot... especially in late June and into July and August.

Because of our close proximity to the Gulf of Mexico and our lower latitude in the United States, it is a foregone conclusion that we have to deal with our fair share of hot, humid days as we head through the summer months. You know those days I'm talking about... where you step outside and it feels like the inside of a dog's mouth, or you try to take a breath after walking across the front yard, and it feels like you're trying to breathe in butter. Humid air doesn't allow as much sweat evaporation from our skin when we are out in the heat. That limits the amount of cooling our body is able to do, making the heat more uncomfortable for us. A breezy day or a day with lower humidity will allow for more evaporation of sweat on our body, allowing us to cool more efficiently.

The heat index is what the "feels like" temperature is to our body, due to the temperature and amount of moisture in the air, and how that affects the ability for the body to cool due to evaporation.

Check this out. A warmer temperature is able to have a much higher heat index with the same value of relative humidity. This is because the warmer air is, the more capacity it has to hold moisture. A good value for a direct measure of the amount of moisture in the atmosphere is the dewpoint. The dewpoint is the temperature the air mass must cool to in order to be saturated with water vapor. A higher temperature air mass can have a higher dewpoint, and because of that, can allow more moisture. Because of this, an air temperature of 92 degrees can have a much higher heat index with a 60% relative humidity than it would be able to if the air temperature is only 80 or even 86 degrees.

The most important things you can do to stay safe from heat exhaustion and/or heat stroke this summer are to stay hydrated (water is best, with sports drinks a close second) and to take breaks from exertion when possible. Some people are not able to do so because of their jobs, but when it is possible, try to limit strenuous outdoor activities to cooler parts of the day. Wearing lightweight, light-colored clothing also helps. These are simple common sense things that we all already know, but it never hurts to have a reminder.

The interior of a vehicle is a death trap waiting to happen in the summer, but even in not-as-hot times of the year. With an outside air temperature of 90 degrees (our average high in July), the interior temperature of the car reaches 109 degrees after just TEN MINUTES and is over 120 degrees in just under half an hour! This is life-threatening heat! Even with a temperature of only 75 degrees outside, the temperature of the car interior exceeds 100 degrees in under 20 minutes! Even with the window cracked or rolled down, this only slightly delays the heat, and the interior temperature still exceeds 120 degrees in under 30 minutes, and still exceeds 130 degrees in less than an hour. Never leave your children or pets in an unattended car, whether the window is cracked or not, or whether the A/C is running or not! Aside from the dangers of the car being taken, the car can turn off or otherwise stop running, and the A/C get turned off. Children or pets can bump controls and turn the cooler air off. Then, the temperature climbs dangerously and rapidly.

On average each year, 38 children die in the United States due to heatstroke while in a vehicle. In 2020, the number was likely reduced significantly because of COVID impacts on travel. Before that, the two previous years had each had 53 deaths. So far this year, we have already had two deaths. The majority of these are careless accidents, even though we sometimes hear news stories about a few of these cases being admittedly intentional. (We won't touch the topic of how many of them aren't admittedly intentional, but likely are intentional). These are completely preventable deaths. It takes the most basic amount of common sense to avoid this. Never leave a child or a pet (or any person of any age not capable of getting themselves out of the vehicle) unattended in a vehicle, whether you leave the A/C running or not or whether you leave the windows down or not. It's as simple as that. Do your part to lower these needless deaths.

A big danger to pets in the warmer months is the temperature of pavement, concrete, and other hard surfaces that they may have to walk on. During the overnight hours, radiational cooling allows the air temperature, as well as the temperature of surfaces, to cool. Pavement will retain a little more heat than grassy surfaces, and its temperature will be a little warmer. During the daytime hours, that dark pavement surface will absorb and hold much more heat than the grass, making the surface of the pavement much hotter.

Think back to heat waves of the past and how you've seen news anchors do the trick of frying an egg on the pavement. It's because the pavement temperature can sometimes really get that hot! Pavement, cement, and AstroTurf can sometimes be as much as 25 to 35 degrees warmer (or even higher than that) than the temperature of a naturally grassy surface. Pavement temperatures that run 120-140+ degrees can severely burn an animal's feet in a minute or less (often immediately of coming within contact with the surface). If you reach down to feel of the pavement or sidewalk, and it is too hot for your hand, it is too hot for the pads of your pet's feet. It is best to walk them on a grassy surface instead.

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