People are looking to make meaning after the global pandemic. And one way that some of us do this is to credit coincidences the unexpected concurrence (同时发生) of events — with helping to find jobs, friends and spouses, make significant career decisions and relieve pains. Scholars disagree on the cause of coincidences. Some say they are random and due to probability. Others see God or spiritual forces at work. Still others say it’s our subconscious making connections. No matter the cause, people who study coincidences say that paying attention to these moments may help us, especially in times of stress.

Studies show that noticing coincidences may help boost both the effectiveness of psychotherapy and mental well-being. Michael Schauch, 42, an investment-portfolio manager in Squamish, British Columbia, who is an avid mountaineer, lost his best friend Brent last year. A few months later, Mr. Schauch climbed a mountain he and Brent often scaled together. At the summit, Mr. Schauch found hundreds of ladybugs. When he climbed a different mountain on the anniversary of Brent’s death, he saw a ladybug a she started up each new section of the rock face. “I knew at once that it was Brent, and that he was still there with me, as if to say: “You’ve got this, Mike. Keep going!” he says.

Coincidences can make the world feel like it makes good sense, says David B. Yaden, an assistant professor at the Johns Hopkins University School. Varieties of spiritual experiences show a correlation (关联) between coincidences and an increase in positive emotions, better personal relationships and a greater sense of meaning in life. Coincidences are more likely to happen to certain people. “People who are troubled by distress and searching for signs: are more likely to experience coincidences,” says Bemard Beitman, a psychiatrist and a coincidence researcher. If you’d like to enhance your ability to notice coincidences, there are several strategies, says Lisa Miller, a clinical psychologist: Be open to them. Write them down. Talk about them with others. “We really need this deep inner wisdom.” she says.

Many are familiar with the potentially deadly danger caused by lightning, which is blamed for an average of 43 deaths in the United States each year, based on data from 1989 to 2018. However, the researchers recently uncovered a surprising and beneficial impact of lighting.

Published at the end of April in Science, the new study found that lightning may play a bigger role in global climate change than what was previously known by the   scientific community, “Lightning increases the atmosphere's ability to clean itself,” the researchers wrote in the study.

The study, which included efforts from nine atmospheric experts across a dozen universities and meteorological agencies, was based on an airborne research flight conducted by a NASADC-8 storm-chasing plane in 2012. The plane used to examine the top part of the top part of thunderstorm clouds, which are known as anvils (砧状云).

According to Dr.William Brune, a professor of meteorology and atmospheric sciences at Pennsylvania State University and co-author of the study, researchers initially thought there was a problem with the equipment on the plane, which was being used to measure the hydroxyl radicals（羟基自由基）in the atmosphere. But soon they realized the sharp increase they observed came along with lightning flashes.

Hydroxyl radicals, described as a “chemical cleaner” by Science Direct, are important chemical compounds (化合物) found in the atmosphere due to the reactive nature with other organic molecules (有机分子).

Researchers previously understood that lightning could help to clean the atmosphere, but there was no evidence that it could produce compounds like these radicals. As a result, the study estimates that somewhere between 2% and 16% of the cleaning that happens naturally in the Earth's atmosphere, is done by lightning.

Why is this significant? The existence of the hydroxyl radicals helps to reduce chemicals like carbon dioxide and methane in the atmosphere. These chemicals, known for greenhouse gases, have been proven to contribute to rising temperatures associated with climate change.

You’re in the shower. You grab the showerhead. What do you do? You sing.

Have you ever wondered about this phenomenon? Some of us wouldn’t sing in public if someone paid us. Yet we’ll sing in the shower without embarrassment. Believe it or not, there’s a scientific explanation behind it.

First, let’s look at why we’re relaxed enough in the shower to burst into song. Think about it: you don’t sing when you’re sad (unless you’re singing the blues, of course). For many people, shower time is the only time they’re alone all day. You’re in a warm, small, safe environment. You’re comfortable enough to be yourself! When you relax, your brain releases dopamine (多巴胺), which can give your creative juices an extra kickstart.

Warm water is rushing over you, and now you’re relaxed and feeling good. It turns out that singing makes you feel even better. Singing, because of the breathing you put into it, gets more oxygen into the blood. This gives you better circulation, which in turn improves your body and mood. And because you have to breathe a little deeper to belt out a song, you get some of the same relaxation and mind-clearing benefits as meditation (冥想). Another neat thing is that when you’re singing, you really can’t think about your problems—more stress relief.

But the best thing about singing in the shower? The acoustics (音响效果)! You can never ask for a better sound system than a bathroom. Because bathroom tiles (墙砖) don’t absorb sound, your voice bounces back and forth around the room before fading away, which makes your voice hang in the air longer. And because the shower is a small space, it boosts your voice, making your singing sound more powerful. So you will sound better than you actually are, which is a confidence boost.

We don’t sing in the shower simply because we have “Call Me Maybe” stuck in our heads. It turns out we do it for many reasons: stress relief, happiness, great acoustics, or maybe just because we like to hear our own voices. Whatever the reason, keep it up. It’s good for you. And if you’ve never tried it, pick a song, grab the showerhead and put on your own private concert.