How does updraft actually happen? Why is it low pressure on high altitude but low temperature as well? Does the air pressure remain low at the mountain peak right before mountain breeze?
ps I have never studied geography before sincerely.
In: Earth Science
It’s easier to think of them like this:
Pressure is how often molecules in the air hit each other.
Temperature is how fast the molecules are moving in the air.
High in the atmosphere there isn’t anything heating up the air (causing the molecules to move) and since there’s so few molecules they don’t often collide either.
An updraft forms when air is rapidly moving upwards to replace moving air from above. The atmosphere will warm of get cooler as you go up the lower levels and assuming the air aloft is colder than that of the ground you can get lift, which then initiates a bunch of other processes that would result in strong updrafts and storms.
When the sun shines it doesn’t warm up the air – air is very difficult warm up this way. It heats the soil which in turns heats a very thin layer of air above it. As this air heats up, it starts expanding and its density falls – thus creating the buoyancy force ([https://en.wikipedia.org/wiki/Archimedes%27_principle](https://en.wikipedia.org/wiki/Archimedes%27_principle)). This process is called convection. Warm air near the surface starts rising. As it rises, it goes through layers of ever lowing pressure and then it starts expanding. As it expands – it cools down. If its humid, there will be additional heat generated by the condensation – but this is beyond ELI5.
Mountain breeze is a more complex phenomena. Air above the peaks is warmer than the surrounding air – that is air at the same altitude but above the valley. This air starts rising and “sucks in” air from down the valley creating the mountain breeze.
Latest Answers