Do Now Sometimes very cold air can blow over the ocean and or large bodies of water like lakes. In certain cases the water may be warmer than the air. As the cold air passes over warm water, it picks up moisture. When the air reaches land it begins to rise. Based on this information, what type of weather could form over the land?

Do Now Which way do the surface currents flow in the northern hemisphere? In the southern hemisphere?

Explain how currents affect climate Objectives Describe and identify factors that form and control deep and surface currents. Explain how currents affect climate

Agenda Today we will: Day 1 Complete a do now. Take notes from teacher presentation. Day 2 Complete a group activity. Exit ticket.

Vocabulary Ocean current Surface current Deep current Upwelling

Currents Ocean water contains streamlike movements of water called ocean currents.

Surface Currents Horizontal, streamlike movements of water that occur at or near the surface of the ocean are called ocean currents. Surface currents are controlled by three factors: global winds, the Coriolis effect, and continental deflections.

Surface Currents, continued Global Winds Winds that blow across the Earth’s surface create surface currents in the ocean. Different winds cause currents to flow in different directions. The Coriolis Effect is the apparent curving of moving objects from a straight path due to the Earth’s rotation.

The Coriolis Effect Click below to watch the Visual Concept. E:\~~2014-2015 Lesson Plans\7th Grade\Unit 3\MS-ESS2-6 Ocean Currents\H3\80215.html

Surface Currents, continued Continental Defections When surface currents meet continents, the currents deflect, or change direction.

Surface Currents, continued Taking Temperature Currents are also affected by the temperature of the water in which they form. The next slide shows Earth’s surface currents. Warm-water currents are shown as red arrows, and cold-water currents are shown as blue arrows.

Deep Currents Streamlike movements of ocean water located far below the surface are called deep currents. Deep currents are not controlled by wind. Deep currents form in parts of the ocean where water density increases. The density of the ocean is affected by temperature and salinity.

Deep Currents, continued Formation and Movement of Deep Currents Differences in water density cause variations in the movement of deep currents.

Surface Currents and Climate Warm-Water Currents and Climate Warm-water currents create warmer climates in coastal areas that would otherwise be much cooler.

Surface Currents and Climate, continued Cold-Water Currents and Climate Cold-water currents keep climates along a coast cooler than the inland climate year-round.

Surface Currents and Climate, continued Upwelling is the movement of deep, cold, and nutrient-rich water to the surface of the ocean. The nutrients that are brought to the surface support the growth of plankton. Plankton support larger organisms, such as fish and seabirds. Upwelling is shown on the next slide.

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