Students construct climographs showing both precipitation and temperature for 3 coastal cities and describe how ocean surface currents affect climate on nearby land. They are provided with the research question, “Do ocean currents influence climate?” and are asked to construct a hypothesis. The students are asked to read an introductory paragraph explaining the relationship between the temperature of the ocean current and temperature and precipitation on adjacent land and examine a map of major ocean currents. They construct 3 climographs using data provided. The labels on the graphs are not directly on the lines, so the teacher would need to instruct students on the placement of their data points. Conclusion and analysis questions are provided asking students to examine the direction of flow of ocean currents, temperature of the water, source regions of the current, and impact on both temperature and precipitation on coastal regions. Extension activities include researching additional information on vegetation, culture and physical geography of the 3 cities studied, plus comparing data for 2 additional cities. The activity should take 2 class periods.
Please note that the information provided in the Introduction simplifies the relationship between ocean currents and precipitation. Global precipitation patterns are created by the convergence of trade winds at the Equator which then rise at that latitude and descend at 30 degrees north and south of the equator. Descending air creates high pressure systems which do not create precipitation. In the southern hemisphere trade winds also blow from east to west, so the wind in Chile is blowing from the land creating dry continental air masses. These factors create the desert climate in Arica, Chile. In contrast, the 2 cities in the northern hemisphere are impacted by the warm ocean currents. Warm water evaporates more easily than cold, causing a warmer and wetter climate than locations further inland at the same latitude.