Tides Exercise - Biology 317 - Field Marine Biology (Due on Friday at Cabrillo Marine Aquarium Feb. 12, 2025 at beginning of class - 10 pts.)

It will be necessary for you to either print this page out in order to draw tide diagrams, also printing out a blank piece of graph paper (see step 3). Alternatively, you can scan your hand- or tablet-drawn answers and turn it in electronically before class on Feb. 12.

This exercise introduces a phenomenon central to our course: the tides. Answer the following questions, using the tide table linked for: LA Tides monthly calendar. (Tips: You can always find this same link at the top of our Course home page and consider bookmarking this link in your web browser!). Note also that I might include a question on our first midterm exam that will challenge you to accurately draw at least one tidal cycle, including drawing the cycle and labeling both y- and x-axes (tidal height in feet and hours of at least one day, respectively) appropriately. You have been warned.
Note that you can select the month displayed, which is important below for comparing the first two Fridays of February during our semester.

1. In the tide table linked above, find and list the times (AM/PM or 24-hour format) and tidal heights (in feet) for the four high or low tides for the 1st Friday of February 2025. Repeat for the 2nd Friday of February 2025.

1st Friday: a)____:____  _________ft. b)____:____  _________ft. c)____:____  _________ft. d)____:____  _________ft.

2nd Friday: a)____:____  _________ft. b)____:____  _________ft. c)____:____  _________ft. d)____:____  _________ft.

2. Navigate to NOAA's webpage with a flexible interface for displaying tides for Los Angeles and vicinity. Create graphs for a three-day cycle for the first and second Fridays of February 2025, starting a day before and a day after each Friday by adjusting the dates. After you adjust the dates, click on "Plot Daily" under "Update". I recommend that you make a screen capture of each graph, for your own use in completing step 3.

3. Draw a reproduction of each graph carefully, ideally on the top half of a piece of graph paper (you can print out a blank graph paper page here). Your y axis should be tidal height in feet, with values ranging from -3 ft at the origin to about 8 ft. Your x axis should be spaced to span three days, labeling every six hours (i.e., 0, 6, 12, 18, 0, 6, 12, 18, 0, 6, 12, 18, 0).

4. True/False (circle one) The tidal height is changing faster midway between high and low tide than it is at or near low tide.

5. What is the duration between the first Thursday's LLW and the 1st Friday's LLW tide? Please be as precise as possible.

6. Study what is mean by mixed tides in our text (p. 41). Explain what this means in terms of the observed tidal cycles. Please note that the typical pattern is abbreviated in the following order: HHW, LLW, LHW, HLW, so the most extreme low tide directly follows the most extreme high tide. Apply these labels to each of your graphs.

7. Repeat steps 2-4 starting with the 2nd Thursday (i.e., make a graph for tides spanning three days, one week later).

8. Study the difference between "spring" and "neap" tides after reading the section on tides in our text. There are also good web sites that explain tides. Assign one of these terms ("spring" or "neap") to each of the graphs that you drew. Explain your assignments in terms of the lunar cycle (i.e., new, first quarter, full, third quarter) in the following space:

9. In terms of how low the tides during our Friday afternoon field trips, how do the upcoming Friday lower low tides compare with the lunar cycle? How do you look up the lunar cycle? (Hint: Most calendar apps allow you to install a lunar calendar, and you can also consult our course field trip schedule here.)