What is wind chill many ask? Well the wind chill factor takes into account wind speeds and humidity, to assess how the human body actually feels temperature.
The 'feels like' temperature is different to the actual air temperature shown on a weather forecast. The 'feels like' temperature measures the expected air temperature, relative humidity and the strength of the wind at 5 feet (human height) as well as an understanding of how heat is lost from the human body during cold and windy days.
The wind chill temperature is especially important on windy days due to the effect of wind on the evaporation speed of moisture from skin, the stronger the wind, the faster the cooling of the skin. This has the effect of moving heat away from the body and making the surrounding air feel colder than it actually is.
For example, on a calm day, our bodies insulate us with a boundary layer which warms the air closest to the skin. If it is windy, the wind will take the boundary layer away and the skin temperature will drop making us feel colder.
When the wind speed is low when it's hot in the summer, the 'feels like' temperatures become more impacted by the humidity level. When a human perspires, the water in the sweat evaporates leading to the cooling of the body as the heat is carried away. When humidity is high, this evaporation reduces, resulting in 'feels like' temperatures that appear warmer than the actual air temperature.
Meteorologist Brittney Merlot breaks all of this down for you in the video above with graphics to illustrate the science behind what is actually going on!