Question: Why does my nose run when I come inside from the cold?

“Cold Nose” LASZLO ILYES, via Wikimedia Commons

Thanks Hannah from Canberra for the question!

Your nose and sinuses are making mucus (that’s a fancy word for snot) all the time, to keep themselves moisturised and clean. There are little microscopic structures a bit like hairs or tentacles called cilia in your nose and sinuses and, normally, they move the mucus to the back of your throat and eventually it mostly gets swallowed.

When it gets cold, those cilia don’t work as well. They can’t move the mucus quickly enough. To make their job even harder, the mucus gets thicker and stickier when it’s colder, just like honey or syrup does. Your nose might start making extra mucus, too, because of the harsh, cold, dry air. This means you get a build-up of mucus in your nose.

When you come inside and the mucus warms up and gets runnier again, your cilia can’t get it moving quickly enough, so it start to run out of your nose.

A runny nose in cold weather doesn’t necessarily mean you’re getting sick, it’s just a normal reaction to going out into the cold from a nice, warm place!


Click for more on your cilia and the cold and the fluid dynamics of mucus. (External links, technical content.)

If you want to know more, think I’ve made a mistake, or have a completely unrelated question, please comment here or jump across to my Ask a Question page to let me know what you’re thinking!


Question: Where does lightning come from?

Cloud to cloud lightning in Zwickau, Germany. By André Karwath, via Wikimedia Commons

Thanks Ashlynn from Adelaide for being my first asker!

Most of us have no doubt had the experience of getting little electric zaps from walking in sneakers on some carpets, or taking off a woolly jumper. If you have fuzzy synthetic blankets you’ve almost certainly seen them, too!

These little sparks happen when certain materials rub against each other. Lightning works a similar way, just on a dramatically larger scale. Continue reading

Space for One More at the Periodic Table

In a huge international collaboration, a team of scientists have made a few atoms of element number 117, confirming work done by a Russia-USA collaboration in 2010 and securing the new element a place on the periodic table.

The results, published in Physical Review Letters this week, describe how the team of 72 scientists from 17 different labs across 11 countries made and detected the new element, and also found new forms of dubnium (element 105) and lawrencium (element 103) in the process.

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Plastic, Heal Thyself!

Wouldn’t it be nice if when your stuff broke, it could just fix itself, like how a living thing can heal a wound?

Self-healing materials have been a hot topic in science research for several years now. There are a few different ways people have tried to make this work, but a group of German scientists led by Professor Christopher Barner-Kowollik have come up with a system that is fast, heat activated and can heal and re-heal apparently indefinitely.

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Quantum Dots for Solar Cells

PMMA (clear plastic) with the new quantum dots embedded.

PMMA (clear plastic) with the new quantum dots embedded.


Researchers at the Los Alamos National Laboratories,  in collaboration with scientists from University of Milano-Bicocca,  have created a new type of quantum dot which could allow the windows of your house to be converted into a new type of solar cell. Previous types of quantum dots have lacked a particular feature called a Stokes Shift which barred them from this use.

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