is the

ninja A or was a covert agent or mercenary in feudal Japan. The functions of a ninja included reconnaissance, espionage, infiltration, deception, ambush, bodyguarding and their fighting skills in martial arts, including ninjutsu.Kawakami, pp ...

art of understanding and using

meteorology Meteorology is a branch of the atmospheric sciences (which include atmospheric chemistry and physics) with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did no ...

as a strategic weapon. It allowed ninja to foresee weather changes and to use them as an advantage. By knowing nature's changes, animal behaviour, or atmospheric/astronomic signs, one could use rainy weather or a hot sunny period as strategic elements to weaken and defeat the enemy.

References

Ninjutsu skills {{Martialart-stub