Who Decides the 30% Chance of Rain?
Who Decides the 30% Chance of Rain? — Few things in the world are certain. But if we can say "how likely" in numbers, we can prepare more wisely. Knowing it's 30% lets you decide for yourself whether to grab the umbrella.
The forecast says "30% chance of rain today." But isn't that strange? It either rains or it doesn't — so where does "30%" come from? Does 30% mean it will rain, or it won't?
For old farmers, weather meant survival. No rain ruined crops; too much caused floods. So people read the sky like an oracle: "red sunset means a clear tomorrow," "low-flying swallows mean rain." This was the wisdom of experience — sometimes right, sometimes wrong. People kept asking: how can we predict more accurately?
The heart of probability is counting: "out of 100 identical situations, how many times did it happen?" The weather service uses computers to find all the past days with weather like today (temperature, humidity, wind, clouds). If there were 100 such days and it rained on 30, that's a "30% chance of rain." So 30% means "on 10 days like today, it rained on about 3." It's not that it rains "a little" — it's the likelihood of rain.
- Weather forecasts (national weather supercomputers analyzing decades of data)
- Hospitals: medical statistics like "this surgery has a 95% success rate"
- Insurance: premiums set by calculating accident probability
- Game loot boxes (gacha): "1% chance for a legendary item" is the same math
占 (jeom) comes from reading the cracks on a turtle shell (卜) and interpreting them by mouth (口) — ancient divination. If the ancients' 占 was "reading the future from experience," today's probability is "reading the future from data." Only the tools changed; the wish is the same.
Meet this hanja in Cheonjamun →Few things in the world are certain. But if we can say "how likely" in numbers, we can prepare more wisely. Knowing it's 30% lets you decide for yourself whether to grab the umbrella.
