Water boils at lower temperature on high altitudes because

Concept:

• The force per unit area is called as pressure.
• As we go on higher altitudes the atmospheric pressure decreases.
• The heat required to change the phase of any substance without changing the temperature is called as latent heat of that substance.
• The temperature at which water starts boiling is called as boiling temperature of water.

Explanation:

• When we go on higher altitudes then the atmospheric pressure decreases.

• Due to decrease in atmospheric pressure it takes less energy to bring the water at their boiling point.
• Hence due to less energy needed, the water boils at lower temperature.
• Unlike Pressure Cooking where the boiling point is higher, the higher-altitude cooking is accompanied by lower/decreased atmospheric pressure.
• This requires more cooking time.
• Water boils at 212º F at sea level. 
• At higher altitudes, the boiling point of water decreases, which leads to longer cooking times.