Water boils at lower temperatures, therefore:
Moisture evaporates more quickly.
Food can more readily dry out during cooking or baking.
Steamed or boiled foods will take longer.
Lower air pressure, therefore:
Baked goods using yeast, baking powder, baking soda, egg whites, or steam may rise excessively, then fall.
At high altitudes, bread rises higher and flour tends to be drier than at sea level. If you live in an area that is more than 1,000 feet above sea level, make these adjustments for cakes, cookies, and yeast doughs.