ROCHESTER, NY (WROC) – Have you ever wondered why the shore of the lake is often so much cooler in the spring and summer than places farther from the lake? Our beloved Lake Ontario is unsurprisingly a huge influencer of our local weather and climate, and the phenomenon you can thank for that is known as the lake breeze.
A lake breeze can be defined as a local change in the wind blowing from water to land (usually from a lake or ocean) caused by temperature differences between land and water. Lake breezes play an important role in our weather here in Rochester as they can have a dramatic effect on temperatures in our area.
This small-scale breeze often occurs in late spring, summer, and early fall when the temperature of our land begins to exceed the temperature of the colder water. It is also helpful to have calm large scale conditions, such as a high pressure system overhead, where large scale winds will not interfere with smaller scale winds.
Here’s how it works:
On a hot day, the sun will warm the land faster than water due to its high specific heat. Specific heat is defined as the amount of heat or energy required to raise 1 gram of a substance by 1 degree Celsius, or in this case, water. This means that water takes much longer to react to temperature changes than land, making it easier to keep cool after a long winter while the nearby land heats up with the warm seasons.
The warming of the sun during the day causes the earth to heat up and the air to rise since warm air is less dense than cold air. Air rising to the surface creates an area of low pressure since this air is forced to create higher pressure aloft. High pressure always flows to lower pressure, so naturally cool, sinking air creating higher pressure on the surface of the lake will want to flow over warm land. This top-to-bottom airflow is your lake breeze!
You don’t always need large temperature differences for a lake breeze to kick in, but the bigger the difference, the stronger the lake breeze can be.
The deeper the lake, the more effective the lake breeze. If the lake is too shallow, it is more likely to warm faster than a deeper lake. This causes the deeper lake to heat up more slowly and therefore stay cool enough to create the right environment for the lake breeze to form.
Take a look at these current temperatures for the day:
Temperatures this afternoon varied greatly from the lake shore inland. Nearly 14 degrees of temperature difference stood from Sodus to Penn Yan. Even Rochester sat 8 degrees higher than Sodus sat just 5 miles from shore. It really shows how bad local lake breezes can be.