Photo/IllutrationWaves crash along the coast of Kushimoto, Wakayama Prefecture, on Aug. 13 with the approach of Typhoon No. 10. (The Asahi Shimbun)

The word “doyo,” which generally means a midsummer period through early August, is used as a prefix for a number of words, such as food.

The first item that comes to mind is “unagi” (eel), and others include “tamago” (egg) and “shijimi” (freshwater clam).

People eat nutritional food when the brutal heat of summer causes one’s appetite and stamina to wane.

Doyo is also a qualifier for weather-related phenomena.

“Nagi” is Japanese for dead calm at sea, and “doyo nagi” means a windless, extremely hot condition. A cool breeze that springs up is referred to as “doyo ai.”

Japanese have warned against high waves that tend to rise around the doyo period, describing them as “doyo nami.”

These waves are generated by typhoons over the oceans. Although the doyo period is already past, approaching Typhoon No. 10 apparently brought high, treacherous waves.

A number of people were killed or went missing along the Pacific coast on Aug. 12.

In Tateyama, Chiba Prefecture, five bathers, all men, were swept offshore. Three managed to swim back, but two--aged 18 and 19--went missing.

It is believed that strong rip currents were generated by waves breaking along the shore and ebbing.

According to the website of the Japan Lifesaving Association, a rip current can travel at a speed of 2 meters per second, which can be difficult even for Olympic medal-winning swimmers to go against.

Everyone must pay close attention to the movement of the waves.

The slowness with which Typhoon No. 10 is traveling is frustrating. This supersize typhoon, whose wind area can almost cover the main island of Honshu, is moving at the speed of a bicycle.

I worry about its impact on summer events taking place around Japan, such as the Awa Odori dance festival in Tokushima.

We must all remain alert during this season.

--The Asahi Shimbun, Aug. 14

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Vox Populi, Vox Dei is a popular daily column that takes up a wide range of topics, including culture, arts and social trends and developments. Written by veteran Asahi Shimbun writers, the column provides useful perspectives on and insights into contemporary Japan and its culture.