Using a wind chill calculator can help you plan for outdoor activities, especially in extreme weather conditions. It gives you a better indication of what it actually "feels like" outside versus what the thermometer says.
But what the heck is a wind chill calculator, and what does it tell us about outside conditions? What's more, how did we come up with the idea of wind chill in the first place? Below, we answer those questions and more.
A wind chill calculator gives you the "feels-like" temperature based on wind speed and air temperature. Instead of having to read a wind chill chart, you add in two numbers and get an immediate calculation.
This online conversion provides a simple and effective way of understanding and preparing for various weather conditions.
There's a caveat. Because wind chill is all about heat loss, a wind chill calculator only works for temperatures at or below 50 degrees Fahrenheit and wind speeds at or above three MPH.
Before we discuss wind chill, let's dig a little deeper into the phenomenon of wind.
When air flows from areas of high pressure to low pressure, it creates wind.
The direction of the wind is the result of the Earth's rotation.
Air can't flow straight from a high-pressure area to a low-pressure area.
Because it gets deflected to the right in the Northern Hemisphere, and, you guessed it, to the left in the Southern Hemisphere.
In this sense then, moving air flows around high- and low-pressure regions.
Wind is the air flow from areas of high pressure to low pressure. It helps move excess heat around the planet circulating it from warmer to cooler regions.
Here's a succinct definition of wind chill: a measure of how cold it feels on your skin when the effects of wind get taken into account.
But there's more to it than that.
Because of convection, or heat transfer, a thin layer of warm air sits just above the surface of our skin.
This layer of heat creates an insulating barrier against our skin.
But what happens when wind disrupts this barrier stripping away warmer air and replacing it with chilly gusts?
In a nutshell, you've got wind chill--the result of heat loss from your body when the warm layer on your skin gets stripped away by fast-moving air.
Wind chill lets you know what temperature your skin feels.
The stronger the wind, the more intense your loss of body heat.
Conversely, if winds remain light, you'll experience very little loss of warmth. As a result, the "feels-like" temperature will coincide closely with the reading on the thermometer.
Wind chill means faster loss of body heat and a more rapid reduction of body temperature to the ambient temperature.
In other words, death can occur in severe weather conditions.
It generates more heat in an attempt to maintain your surface temperature, which translates into even greater heat loss.
In extreme weather situations, wind chill and your body's response to it can lead to:
Good wind chill charts indicate how long it takes for frostbite to set in based on various temperatures and wind chill factors.
In extreme conditions, it can take as little as five minutes for frostbite to set in.
Winter in Florida probably won't lead to many discussions of the wind chill factor. But winter in Iowa sure will.
If you're attempting to scale Mount Everest or take part in extreme winter sports, the "feels-like" temperature could mean the difference between life and death.
To determine the "feels-like" temperature, you'll need to know two things:
Once you have these details, there are also two different ways you can calculate wind chill, using a chart or a forumla.
When you look at the wind chill chart above, you'll see numbers running down the furthermost lefthand, vertical column.
As you go down, these numbers increase, and they correspond to wind speed calculated in miles per hour (MPH). On the uppermost horizontal column, you'll see air temperature readings.
Start by finding the approximate air temperature for your current conditions, and then find the current wind speed. Where those two columns intersect, you have the wind chill temperature.
Mathematically, it's not too difficult to determine wind speed:
In this generalized formula, the T is the air temperature (in Fahrenheit), while V is the wind speed in mph.
Alternatively, you can plug your values into our free calculator to skip the arithemtic.
In 2001, the United States, Canada, and the United Kingdom came together to develop a new wind chill index based on skin temperatures under various wind speeds and thermometer readings.
While producing far more accurate readings than previous developments, this method still raises some important questions:
The measurement is also based on a controversial factor known as internal thermal resistance, or the individual's ability to endure cold temperatures.
Unfortunately, this varies greatly by the individual.
While wind chill is fairly accurate, it does have it's limitations. It doesn't consider your clothing, thermal resistance, altitude, humidity, or position relative to the wind.
Paul Allman Siple and Charles F. Passel created the first rudimentary wind chill tables and formulas while exploring the Antarctic prior to World War II.
They used a little plastic bottle filled with water and suspended from the expedition hut roof to chart the effects of cold air on its contents.
Based on the contents of the bottle and anemometer readings, they crafted the first wind chill index. (Commonly used in weather monitoring, an anemometer measures wind speed.)
The system that Siple and Passel developed provided them with a fairly accurate means of quantifying weather conditions.
By the 1960s, the wind chill equivalent temperature became the predominant way to report wind chill.
The wind chill equivalent temperature equated to the temperature at which the wind chill index would feel the same without the presence of wind.
The early readings exaggerated the extremity of many weather conditions.
It assumed two faulty things:
Charles Eagan came along and adjusted the absence of wind to 1.8 meters per second, or the lowest speed that an anemometer can read.
More accurate representations of actual outdoor conditions.
Paul Allman Siple and Charles F. Passel created wind chill prior to WWII. Though faulty, it was widely used by the 1960's. The formula was later modified by Charles Eagan and standardized between the US, UK, and Canada in 2001.