Weather News

Chill out, winds

Tristan Meyers, Thursday July 14, 2016 - 12:36 AEST

On days like today in the southeast, it feels a lot colder than what the thermometer may read.

There are several different feels like calculators, so different meteorological organisations around the world will use different combinations of the above factors to come up with a "feels like" temperature, and all have their strengths and weaknesses.

The combination of strong winds and icy air create a wind chill factor. One estimate of this is the "apparent" temperature, often listed next to the actual temperature. Interestingly, this apparent or "feels like" temperature has no impact on inanimate objects like exposed water pipes. It solely relates to how fast the human body loses heat and in this sense isn't a directly measurable index, just one to help us humans understand the weather conditions. However, it is quite important since in very cold conditions the wind chill factor contributes to an accelerated development of frostbite on exposed skin.

There are several factors to taken into account in order to calculate this apparent temperature. First is the actual temperature, read by a thermometer. You may notice on days that are above about 20 degrees that wind chill doesn't have as much of an effect. On cold days, it is much more important, such as today in Canberra where at 12pm it was 10 degrees, but felt like five or six degrees.

Second, you need to know the wind speed. The faster the winds are, the quicker heat is transported away from the surface of your skin. Humans can offset this when they create their own body heat by exercising, but it's best just to seek shelter from the winds.

The amount of sunlight should also be taken into account. The sun is a source of heat, and so the sunnier it is outside the more heat could be absorbed by your skin. This helps replenish heat lost from blustery winds.

And lastly, humidity is included in the calculation. However, humidity is more relevant when it gets hot since then it relates to how quickly the body can cool itself by evaporation when you sweat. Summers in Brisbane can often feel 3-4 degrees warmer than what the mercury indicates due to high humidity.

So, what does this mean? Using an example, today and tomorrow in Sydney have an identical forecast maximum of 17 degrees. However, most this afternoon will feel closer to 10-13 degrees, whilst tomorrow it will feel several degrees warmer.

- Weatherzone

© Weatherzone 2016

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