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Ninjas and Meteorology

The ninja knew that successfully forecasting rain and the wind could give them strategic advantages against the enemy. They studied the weather and this was called “tenmon.” Ninjas believed that

  • If there are dew drops on spider nets, it would be a clear weather
  • If there is a large ring around the moon, it is likely to rain
  • If the mountains seem close, it is likely to rain
  • If the stars are twinkling, the next day will be rainy
  • If it is cloudy but not windy, it is not going to rain (fall season only)
  • Ninjas also often set a fire to ablaze the enemy territory. It is very important to know when there will be a smooth dry wind called the “foehn effect” to accelerate the fire. The ninjas used kites in the morning to predict the dry wind in the afternoon.