How to be a Laundry Legend

By Vicki Huang, class of 2020.

For those of us who brave Melbourne’s changeable weather: Give yourself a pat on your back. But let’s especially congratulate Melburnians who hang their laundry outside – which takes extreme skill and courage. To perfect this chore, laundry legends need to consider weather patterns, clothes-line angles and pegging tactics. As someone who has been lectured endlessly about chores, I am here to give you a crash course on scientific laundry hanging.

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Weather Today is the Day

Laundry 101 begins with weather forecasting. You may look at the ​Bureau of Meteorology​ or predict by cloud watching. Laundry-wrecking rain comes from Nimbus clouds. (Yes, like Harry Potter’s broomstick.) The two most common nimbus-types are “nimbostratus” and “cumulonimbus”.

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Look up. Is the sky blanketed with sun-hiding, grey and featureless clouds? If yes, you are probably looking at rainfall-creating “nimbostratus” clouds. These clouds are low in the sky and come from thickening clouds when warm air meets cooler air. With nimbostratus’ present, now is not the time for laundry.

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If you see blue skies and a towering white puffy cloud at a distance, do not be deceived. You may be looking at a “cumulonimbus” which turns good weather into torrential rain and thunderstorms at lightning speeds. These powerhouses grow from harmless cumulus clouds forced over rising hot air known as convection. When the rising air condenses into water, it releases heat to make ​more​ rising clouds. After several cycles of rising and condensing, a towering laundry-destroyer is born. Cumulonimbus’ are also known as thunderheads packing in energy equivalent to 10-Hiroshima bombs.

Laundry-amateur’s may compromise with very little rain. But note, rainfall levels usually reach millimetres per hour whereas laundry evaporates 90% slower. It’s much better to spend your time cloud-watching and wait for a sunny day.

Scoping the Sunniest Spots

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After telling the rain to go away, hopefully, you’ll have decent sunlight. Evaporation happens when water molecules absorb enough energy to turn into gas. Some energy comes from air temperature and long-wave radiation from the ground. However, the biggest energy boost comes from direct sunlight. To maximise evaporation, hang laundry in the brightest spot possible.

Give your lighter, thicker clothes the golden spot. Since they absorb less light, they dry faster than darker, thinner clothes. Check out an article about colour and light relationships ​here​.

Windy spots are also great! When your laundry dries, surrounding air gets wetter. The wind blows away humid air so evaporation happens faster. On less windy days, leaving gaps between clothes lowers humidity around each piece of laundry. Don’t burden your quick-dry t-shirt with a slow-drying towel nearby.

Once you have claimed the perfect spot, it’s time to maximise the surface area exposed. Remember when I said direct sunlight gives the most energy? Avoid folding your wet laundry and try to make it one big flat sheet. Now, face all these sheets north to shrink shadows as the sun moves through from east to west.

If you want to be a laundry luminary, there is always the Penman-Monteith equation. Often used in the agricultural industry to model soil moisture, this equation can also predict laundry drying times. All you need is today’s temperature, humidity and wind-speeds for a laundry-weather report. In 2011, University of Leicester researchers did exactly that – providing us laundry enthusiasts with ​instructions​ to perfect our craft.

Thank you for attending Laundry 101. Go forth and do great things with your laundry.



The Science of Drying by MetService: ​

National Geographic Clouds: ​

Cumulonimbus cloud over Africa:

Do you want to hang out?​ in the Journal of Physics, University of Leicester: