Friday, May 4, 2012
"Marine layer" over Lake Champlain
Ecological notes: Some things are so beautiful a naturalist type of explanation seems so paltry in comparison. I will say that looking out over the thin layer of clouds sweeping across the lake reminded me of being back in California. Some early morning hikes in the Santa Monica Mountains took me up the hills out of the fog and above the low marine layer. I could look out over the Pacific Ocean and see only the Channel Islands and occasional peaks in the chain of Santa Monica mountains poking their ancient noses above the clouds.
Here's where it gets nerdy: we get those marine layers in Southern California all the time because the water is relatively cool (particularly near Point Conception in Santa Barbara) and the air often significantly warmer. When you get a really warm air mass moving over a relatively cool body of water. The water cools the air nearest the surface, and as it cools it gets denser, effectively getting trapped beneath the warmer, less dense air above. If the air mass cools enough, water vapor will condense out and form clouds (similar to pushing warm air up a mountian - as it rises it cools and forms clouds, which explains why Camel's Hump is always covered in clouds). This cold layer effect is exacerbated when you have a low pressure system that lifts the warm air and makes the trapped cooler layer thicker (as we did tonight). We just had all that rain and the air was warm (67 when I took the photo) so the air was humid to begin with (87% on weather.com), so all the conditions were right for a cool little marine layer.
Where: Lake Champlain and Juniper Island