G7 -Ocean Currents Lower-02

Introduction

Your Mom chuckles as you and your sister return from the shortest swim ever. You think to yourself, “Mom knew! She knew the water was cold before we jumped in.” You grab the towel from her hands and wrap yourself in it.

After a moment, you observe that many people are wearing wet suits. You are familiar with wet suits. Surfers in Texas wear them in the winter months when the water gets cooler, but this is July. True, this is Los Angeles and not a city in Texas, but it’s still summer, right? Why isn’t the ocean warm?

In Texas, the warm water of the Gulf of Mexico is warmed even further in the summer months. That’s why the Texas coastal air is moist and humid in the summer. A short walk to the mailbox will cause anyone to start to sweat. The air in California does not seem as humid. You didn’t really think about it until now, but you don’t seem to sweat as much, even on the hottest of days. You wonder if the lower humidity could be connected to the cold ocean water.

A little research when you get home reveals some interesting facts. Clearly, you won’t be going to the beach until you buy a wet suit. The water that you will be swimming in travels south from the coast of Alaska. You think to yourself, “No wonder it is so cold!” You also make the connection between the cold current and the humidity. Warm water would evaporate more quickly than cold water. This makes sense to you; there is less water vapor in the air. Even more interesting, you read how currents travel around the globe. The motion of these currents helps to regulate Earth’s climate.

The Ocean’s Conveyor Belt

Thermohaline circulation is also known as the ocean conveyor belt. This conveyor belt is the cause of ocean currents. These currents, caused by density, help to regulate ocean temperatures. These changes in density are caused by two factors. The first is the ocean’s surface temperature. Warm water is less dense than cold water. The other factor is the amount of fresh water entering the ocean system.

Fresh water is less dense than salt water. These natural events, in combination with the wind-driven surface currents, are what distribute heat around the globe.