The more we move higher in the atmosphere, the more pressure reduces. This isn't supportive for mountaineers when cooking. Why? Because of the effect of pressure on boiling point.
An increase in pressure at the surface of a liquid raises the boiling point of the liquid and conversely, a decrease in pressure lowers the boiling point of the liquid.
The efficiency of cooking is proportionate to the heat of the system. In other words, if there was a way to increase the boiling point of the liquid in the pot, probably water(100°C), then cooking would be much easier, especially for those who live on the mountains.
Luckily, there is a solution – The Pressure Cooker.
The pressure cooker is a practical application of the effect of pressure on the boiling point of a liquid. It is a strong metal saucepan with a lid, just like every other saucepan but it can be held down tightly. There is a loaded pin valve on this lid which controls the flow of steam produced when the water in the container is heated.
Food is cooked much faster in the pressure cooker because the increased pressure of the trapped gas above the liquid raises the boiling point of the liquid inside the cooker to a temperature greater than or equal to 120°C. Thus, a high cooking temperature is reached very fast, thereby reducing the cooking time and saving fuel.
Because of this property of the pressure cooker, it is indispensable to mountaineers, since the atmospheric pressure at those heights is very low, even to lower the boiling point of water below 100°C. Without a pressure cooker, cooking on the mountains will be hell.
References
2016 edition school Physics