Baking in the Clouds by Hedy Goldsmith in How-to, September 1st, 2012
Living at sea level, I’ve never given much thought to recipe adjustments needed when baking at higher elevations. A dear friend of mine (a seasoned pastry chef), Tweeted that she was nervous about baking in the clouds — it was a cry for help. I was happy to chime in and give her thin-air solutions.
First things first: Boiling water temperature is not universal. At sea level, water boils at 212 degrees F. At 10,000 feet above sea level, it drops to 195 degrees F. Go figure.
If we understand why cakes fall during cooling, fixing the problem becomes easy.
Follow me: the higher up you go, air pressure decreases, which causes leavening agents in baked goods to react too quickly. Liquids also tend to evaporate at a quicker rate. This causes cakes to fall and be dry.