# Wind Chill Calculator

The wind chill calculator allows you to calculate the lowering of body temperature due to the passing flow of low temperature air. The result is known as the wind chill factor.

 Wind Speed Units:Miles per hour (mph)Kilometers per hour (km/h)Meters per second (m/s)Feet per second (ft/s)Knots (kts) Wind Speed: Temperature Units:Fahrenheit (°F)Celsius (°C)Kelvin (°K) Air Temperature (°F):
 Fahrenheit (°F) Celsius (°C) Kelvin (°K)

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The Frostbite risk Chart below provides the associated exposure times associated with the colour code on the Wind Chill Factor Chart.

## Why do I need to know the wind chill factor?

It is important to understand the wind chill factor if you intend to complete exercise in cold weather or work outside in cold temperatures (perhaps patrolling as a security guard). There have been a number of articles that argue the wind chill factor is nonsense but the reality is that we all feel the difference in temperature as the wind speed increases and how it is amplified as temperatures reduce. Anyone who suffers with Raynaud's disease will testify to how they the wind chill factor affects them.

When we understand the windchill factor, it allows us to prepare for and manage exposure to the environment more effectively by wearing appropriate clothing or limiting exposure. Controlling your exposure this way reduces the chance of injury, illness and, in extremes, frostbite. We can control our exposure by understanding how heat loss occurs and then controlling that heat loss.

### How does heat loss occur?

All surfaces lose heat via:

1. Conduction: Conduction heat loss occurs when there is a difference in temperature between two solids, gases or liquids which are in direct contact with each other. Heat transfers from the hotter substance to the colder substance with heat transfer faster between solid than liquids and faster between liquids than gases. Good sport clothing uses this science to balance body heat effectively through material design.
2. Evaporation: Evaporation heat loss occurs when heat converts a liquid to gas. In sports, evaporation occurs when the excessive heat caused by the body during exercise causes sweat to evaporate.
3. Convection: Convection heat loss occurs when there is a difference in temperature between the surface and the gases or liquids surrounding it. With wind chill, convection heat loss occurs when the resulting moisture on the surface caused by the temperature difference gains velocity with increased wind speeds. This heat loss is amplified in living being as they exert more energy. A human running for example will produce more surface moisture in the form of sweat. The more areas of the human body that are exposed to the environment in this situation, the higher the rate of heat convection as the moving air removes the insulating boundary layer of war air that naturally occurs during convection heat loss.
4. Radiation: heat loss through evaporation occurs via infrared rays and heat is transferred from one substance to another without the two substances necessarily being in contact.

## What effect does the wind chill factor have?

The wind chill factor makes the temperature feel colder than it actually is. As the colder air flows across the body, the body cools. The faster the speed of the wind, the faster the cooling process occurs.

## How is the wind chill factor calculated?

The wind chill factor is calculated using the wind chill index formula below:

WCI = (10/v - v +10.5).(33-t)
• WCI = Wind Chill Index
• v = wind velocity
• t = air temperature

## How cold is it with the wind chill factor?

Technically, the outside temperature remains the same regardless of the wind chill factor. The wind chill factor Simply defines what the temperature will feel like when factoring in the impact of the wind speed. The temperature that you will feel when factoring in the wind chill factor is displayed on the wind chill index chart.

Wind Chill Factor Chart
Temperature (°F)Wind Speed (mph)
51015202530354045
40363432302928282726
35312725242322212019
30252119171615141312
251915131198765
2013964310-1-2
15730-2-4-5-7-8-9
101-4-7-9-11-12-14-15-16
5-5-10-13-15-17-19-21-22-23
0-11-16-19-22-24-26-27-29-30
-5-16-22-26-29-31-33-34-36-37
-10-22-28-32-35-37-39-41-43-44
-15-28-35-39-42-44-46-48-50-51
-20-34-41-45-48-51-53-55-57-58
-25-40-47-51-55-58-60-62-64-65
-30-46-53-58-61-64-67-69-71-72
-35-52-59-64-68-71-73-76-78-79
-40-57-66-71-74-78-80-82-84-86
-45-63-72-77-81-84-87-89-91-93

## When did the wind chill factor start and who invented the wind chill factor?

The wind chill factor was invented in 1945 in Antartica by two Antarctic explorers, Charles Passel and Paul simple. Their aim was to quantify the effect of wind speed on heat loss. This experiment was quite simple, they filled a plastic bottle with water, suspended it from a pole to minimise conduction heat loss and measured how quickly the water lost heat and turned to ice. Their experiments concluded that the faster the wind speed, the quicker the water lost heat.

## What happens if the wind chill factor is higher than the actual temperature?

The wind chill factor, when calculated correctly, is always lower than the actual temperature. The wind chill factor chart below illustrates this fact. If the effect of the flow of air increases the temperature, you would calculate the effect using the Heat Index Calculator.

## At what temperatures can wind chill increase the risk of frostbite?

In the wind chill factor chart above, we have colour coded the points at which the windchill factor starts to increase the risk of frostbite. The risk of frostbite increases when the temperature reaches -5F and the wind speed approaches 30mph. This chart is indicative as moisture levels and individual body resistance and clothing play a part but the windmill factor chart is a very good gauge.

 Frostbite Times: 30 minutes 10 minutes 5 minutes