Today’s Wonder of the Day was inspired by Adria. Adria Wonders, “Why does water take longer to warm up than air?” Thanks for WONDERing with us, Adria!
Do you have a favorite lake or pool you like to frequent in the summer? If so, you've probably experienced a phenomenon that gets the attention of most swimmers early in the season each year.
As the summer Sun begins to shine brightly, it quickly warms up the air and the land. As you walk toward your favorite lake or pool, your feet might feel the heat of the hot sand or pavement. When your skin heats up, that water begins to look more and more inviting.
When you can't stand to wait any longer, you plunge headfirst into the water. Instead of a refreshing wave, though, you're met with what feels like an icy shock to your system. The air and the land around you may feel like summertime, but the water probably still feels like spring.
Why is that? Why does it take the water longer to warm up than either the air or the land? When the Sun is shining bright, it seems like the water should be as inviting as the air and the land around you.
If you think about your experience with water, though, it makes sense. If you've ever put a pot of water on the stove to boil for a nice spaghetti dinner, you already know it can seem to take forever for that pot to boil. Now think of that lake or pool as a super-size pot of water that needs to be heated by the Sun. It's no WONDER it takes so much longer for it to heat up!
Compared to air or land, water is a slow conductor of heat. That means it needs to gain more energy than a comparable amount of air or land to increase its temperature.
Also, water's fluid structure means its molecules are in a constant state of motion. This results in it taking more time to increase uniformly the temperature of any particular body of water, especially if the heat source is the rays of the Sun.
Although water is a slow conductor of heat, it tends to store heat quite well. That means that, once heated, a body of water will hold onto that heat for a much longer period of time than either air or land.
This is why the world's oceans are one of the most important sources of heat energy that drives the weather. Covering two-thirds of Earth's surface, the world's oceans absorb much more sunlight than the air and the land. They also store and retain that heat longer due to their greater density.
In some areas, ocean waters can have a significant impact on climate. The United Kingdom, for example, is farther north than most of the United States. It enjoys warmer winters than many places at similar latitudes, though, due to the effect of warm tropical waters that make the climate more tolerable than it might be otherwise.