Why is my fridge door harder to open again straight after opening?

Dave - It's a lovely piece of physics, this one. Basically, the magnetic door seal clips on and it makes a really good airtight seal. That means that the fridge is full of fairly warm air from outside then over the next 2 or 3 seconds, that cools down. When air cools down, it shrinks, so it reduces the pressure inside the fridge. So to open that door now, you've got to pull against all that pressure difference and it's really difficult. But if you leave it for a couple of minutes, there are few leaks in there, so the air slowly works its way back in and the pressure is equalised, so it's nice and easy to open again.