The post below was sent as an issue of my newsletter, Ready for Rain.
Back in 2017, when we lived in the yurt-shaped house, we noticed something interesting about warm summer evenings. Just before dusk, a cool and consistent wind blew out toward the water where it created subtle waves as it landed. The wind would last into the night and be gone by morning. When we moved to the guest house during construction, it happened there too. Summer evenings ended with a cool wind whipping to the west.
The wind didn’t seem connected to weather patterns. It was smaller than that; a phenomenon that was too localized to be in a weather report. I asked our neighbors about it and they shrugged their shoulders. It’s just something that happens and always has. The more I watched the westward wind, the more evidence I saw that it was shaping the landscape around us. The tall trees on the south side of our property were bent toward the water.
Whatever the cause, the wind was reliable enough to influence the design of Flattop. A cool and reliable evening breeze at the end of a warm day should not be wasted, so we looked for ways to use it. The big idea was to use the wind to flush out the warm summer air out of the house and replace it with cool evening air. To make that happen, we added operable windows on the east and west sides. Today, I’m happy to report that the system is working. The westward wind is like an air conditioner that kicks on after sunset. All we have to do is open the windows.
This is a prime example of why it helps to live in a location before building there. Wind, sun, and rain are free resources that can be put to work. Observing them for a couple of seasons before breaking ground can be helpful in making a design more efficient.
Despite all the watching and planning, we still didn’t know why the westward wind was happening. That all changed a couple of weeks ago when we hosted a small dinner party that included a retired Coast Guard officer. We talked about the wind and he said, “Oh, that’s a land breeze”. I had heard of a sea breeze before, but never a land breeze. I had to learn more.
What I found is a simple idea. The westward wind is caused by a difference in the air temperature over the land and the sea. When the sun goes down in the summer, the air over the ground cools relatively quickly as heat rises upward. The air over the water cools more slowly. This difference in temperature (and pressure) is what causes the wind. Cool air flows out to the water at a low elevation as warm air rises and circulates back to the land.
What I’ve been calling the “westward wind” was not specifically westward at all. I just happen to live in a place with a large body of water to the west. Maybe it’s really the “waterward wind?” That doesn’t exactly roll off the tongue, does it? Still, it’s probably better than “land breeze” which is rather unremarkable sounding. I’m sticking with the “westward wind” for now.
The sea breeze, which we don’t notice as much, is the opposite. Sea breezes happen during the day and blow from the sea toward the land. This is because the air over the land warms more quickly than the air over the water when the sun is out. It’s also the name of a cranberry, grapefruit, and vodka cocktail that was popular in the 80s. It’s not surprising that there is no “land breeze” cocktail, because who would order that? Does it come with a garnish of dead leaves?
For now, rest assured that the mystery is solved and we’ve all learned a bit more about the weather.