Lesson 3: Wind at the seashore

Activity 1. Pressure and winds at the seashore (day)

This lesson pulls together the concepts of Lessons 1 and 2 by exploring winds at the seashore. Through classroom discussion and activities, students learn how differential air temperatures set up day and night time wind patterns near an ocean.

Online Resource: Simple drawing of land and ocean

Materials:

• Overhead projector or LCD project

Advanced Preparation:

• Read through the procedure before class
• Make an overhead slide of the simple land - ocean drawing or use an LCD projector to show the drawing
• Make a copy of the simple drawing of land and ocean for each student

Time needed: Teacher preparation - 10 minutes; Class activity - 30 minutes

Procedure:

To introduce this activity, ask the students if they have ever been to the beach. Was it breezy? Why? (Note: if the students quickly understand the process, these steps can be condensed.)

1. In your own words, tell the students: "Let’s explore how wind is created when next to large bodies of water and see if we can apply the information we've learned over the past two lessons to this illustration."
2. Hand out the simple drawing of land and ocean to the students
3. Ask your students: If the sun heats an area with both land and ocean, where will the high- and low-pressure areas form during the day? Let’s see if we can figure this out.
4. From the previous lesson, which heated more quickly – land or water? (We learned that land heats up more quickly than water/ocean. Label the land with the word ‘warmer’, and the ocean with the word ‘cooler’)
5. As the air warms does it become more dense or less dense? (It becomes less dense.)
6. What happens when the air heats up? Does it sink or rise? Why? (It rises, because the heated air is less dense than the air above it. Draw an arrow pointing up from the land.)
7. Since there is lower density air above the land, is there high pressure or low pressure? Think about the balloon activity, as the balloon was filled, the pressure increased, and so did the air’s density. Outside of the balloon, the air was lower density and lower pressure. (so Low density = low pressure. There is low pressure over the land. Draw the low pressure symbol ‘L’ on the land)
8. What is happening to the air over the ocean? (Air over the ocean starts to cool and sink toward the ocean. Draw an arrow pointing down towards the ocean)
9. Since the air is sinking towards the ocean, does this mean the density of the air is higher or lower? (It’s higher, which means the pressure is higher)
10. Now we can draw the high pressure symbol (H) to our drawing and connect the rising arrow and sinking arrows together into a circle.

Closing the activity: Ask the students: What does this circle of arrows remind you of? (a convection cell). During the day, you would feel wind from the ocean on your face. What happens at night? (This leads into the next activity.)