Professor Paul Thursday - Is The Bank's Temp. Ever Right?

Many of us have had the following experience. You are driving down the road on a warm summer day. Then, you get stopped at your favorite stoplight, and you happen to see a bank sign flashing the current time and temperature. Next, you look down on your dashboard and your car's outdoor temperature reading gives you another temperature. Lastly, you look at your weather app (hopefully it’s weatherology) on your phone and it has a completely different current temperature displayed. This article is going to smooth out the confusion and let you know which temperature readings can be trusted and which tend to be highly inaccurate. 

First, let's look at the official way in which the ambient air temperature is measured. The National Weather Service (NWS) has a strict protocol for how temperature is measured. In order to be a weather observer these standards must be followed. First, the temperature measuring instrument should be set up in a fairly level region with vegetation or sod below it. It should also be at least 100 feet away from any paved surface. Then, the instrument needs to be shaded so that it does not receive any direct sunlight. This is oftentimes achieved by putting the instrument inside a wooden box that is painted white and has some holes for ventilation. The thermometer then needs to be mounted at a height close to 5 feet above the ground. 

These criteria are essential in making sure the measurement of temperature is as accurate as possible. The biggest reason that bank thermometers are off is that their temperature sensors are likely not being shaded from the sun and they are too close to a paved parking lot. Any paved surfaces heat up to much higher temperatures than other surfaces (this is due to the lower albedo) and then radiate that heat out around it. This explains why car thermometers will read too high on sunny days. The most trusted way to get an accurate current temperature is by looking at your current conditions in your weatherology app. This temperature reading is taken at an approved NWS observation site in your area.