We don’t hate winter (see: bundling, ice skating anywhere), but that doesn’t stop us from all-out crying after two minutes in the cold. Deep-seated emotional pain? Nope—it’s our eyes’ normal biological response.

The Need-to-Know

Your eyes need to stay lubricated to see, which doesn’t go well with cold, dry winter air, says James Auran, M.D., chief of ophthalmology at New York’s Harlem Hospital Center. The wind and lack of moisture leads your eyes to tear up, trying to keep themselves at max visibility and minimum discomfort. It’s basically a reflex response—and when the tears overwhelm your tear ducts, they make a dramatic exit down your cheeks (and nose, so no worries about wiping it on a sleeve).

The lack of humidity makes your eyes tear more, as does brightness: All that light reflecting off snow makes your eyes more sensitive. Recent research has found that your eyelash length also plays a role in how much you tear up. Lashes at one-third your eye’s width best keep tears from evaporating (meaning less reflexive waterworks), with any longer funneling air in and creating more irritation, and any shorter allowing greater evaporation of tears—triggering a flood of them to keep you seeing.Eyelashes divert airflow to protect the eye. Amador GJ, Mao W, DeMercurio P. Journal of the Royal Society, Interface / the Royal Society, 2015, Nov.;12(105):1742-5662.

Your Action Plan

Glasses are your best defense against weeping on the way to work, because the glass creates a tiny greenhouse effect and keeps the air in front of your eyes more humid, Auran says.Any glasses will work, but sunglasses pull double-duty against brightness.

If your eyes are still watering, Auran says to try putting in a few wetting eyedrops before going outside. It may seem counterintuitive—add moisture to stop moisture—but the drops will keep your eyes from going into overdrive. Everyone’s eye sensitivity is genetically different, but if you’re facing excessive wetness and tearing up indoors, check with your doctor to make sure nothing else is up (could be a blocked duct, could be an abnormally small drainage system, or could be nothing, Auran says).

The Takeaway

Tearing is just your eyes’ response to dry winter air, and while it might be annoying to constantly explain that no, you’re not crying, it’s better than living with blurred vision or irritated peepers. Like most things, it comes down to genetics—and also like most things, sunglasses (and eyedrops) will help keep you cool.