Climatologist Brian Brettschneider has explained why some lakes freeze faster than others. The amount of water in a lake is the most important factor, with deeper lakes taking longer to freeze because they have accumulated more warmth during the summer. Other factors include exposure to sunlight, with lakes surrounded by trees taking longer to freeze, and whether there is new water coming into the lake. Streams carrying cooler water can help to freeze a lake faster. Most lakes freeze from the top down, with ice being less dense than water.