Influences of Latitude and Proximity to Water on Climate - Lab Assignment

Unless otherwise indicated, show your work for all problems. You can either enter your answers into this document electronically using a computer or tablet, or you can print this document, handwrite your answers, and scan the pages. If you need additional space, you can insert additional pages or you can add additional space within the Word document. For all numerical answers, the units should be indicated. Students can discuss this lab with each other, but copying from each other or copying from other sources is cheating and is not permitted. You should not share your answer sheets with other students or look at the answer sheets of other students. You should understand the concepts well enough to explain your answers in your own words. If your work relies on information that is obtained from a legitimate source other than ESSE 1012 course materials, please indicate the source of that information with enough detail so that someone else can locate the source. Please see the course outline for detailed policies.

As discussed in class, a key influence on climate is latitude. Latitudes near the equator are typically warmer and higher latitudes are typically cooler. Furthermore, the temperature seasonal cycle amplitude (i.e. the change in temperature between the coldest time of year and the warmest time of year) is typically smaller at low latitudes than at high latitudes. But another important influence is proximity to large bodies of water, especially oceans. We will refer to this effect as the “proximity to water” (PTW) effect.

In this lab, you will look at climate data from the Canada Climate Normals website (https://climate.weather.gc.ca/climate_normals/index_e.html) and assess the influences of latitude and the PTW effect. In addition to the average temperature over the whole year, we will also be interested in the temperature seasonal cycle amplitude.

1.(a) Compute the effective heat capacity for a 150 m deep section of ocean, assuming it is pure water. (3 points.)

(b)Compute the approximate effective heat capacity for a 15 km thick section of atmosphere. Use the vertically-averaged density (0.8 kg m-3) for your calculation. (3 points.)

(c)Compare the effective heat capacities in (a) and (b). How does this lead us to expect that large bodies of water will have a stabilizing effect on temperature? (8 points.)

2.(25 points.) Use data from the Canada Climate Normals website to fill in the table below. Use data from the 1981-2010 period. If multiple stations are available, choose the airport station (indicated with an “A”), as that typically has the most complete data. (Note, type “St John’s” without the period to search for stations in this location.) In the table below, the following notation is used:

1. Compute Effective Heat Capacity of Ocean and Atmosphere

is latitude. You can round to the nearest degree. Note that a single quote indicates minutes, and there are 60 minutes in one degree. So 23o30’ would round to 24o and 23o29’ would round to 23o.
is the warmest monthly average temperature. (Note, this is not the same as the extreme maximum of daily temperature.) Express values to one decimal place.
is the month during which average temperature is warmest. (You can use abbreviations like “Jan”, “Feb”, etc.)
is the coldest monthly average temperature. (Note, this is not the same as the extreme maximum of daily temperature.) Express values to one decimal place.
is the month during which average temperature is coldest. (You can use abbreviations like “Jan”, “Feb”, etc.)
is the seasonal cycle amplitude. Express values to one decimal place.
is the average temperature for the year. Express values to one decimal place.

Note that the elevations of the above locations are all less than 300 m, so elevation differences will not be a significant influence on climate differences between these regions. But do keep in mind that elevation is another potentially important influence on average temperature and temperature variability. Due to the less dense and drier air, an inland location at high altitude will typically have lower average temperature and a higher amplitude temperature seasonal cycle compared to an inland location at the same latitude at lower elevation.

3.Assume winds at these latitudes are mostly from the west, with wind occasionally coming from other directions. Rank the locations 1 to 5 to indicate the relative strength of the PTW effect. A rank of “1” would indicate that the PTW effect is stronger in that location than in the other locations. Explain your reasoning. You can use the maps provided at the end of this document to help with explaining your answers. (14 points.)

4.Rank the locations from lowest latitude to highest latitude. (5 points.)

5.Rank the locations from highest to lowest value of . Use the rankings in questions 3 and 4 to determine whether latitude or the PTW effect explains the differences between the locations. That is, does the ranking by  more closely match the ranking by latitude or the ranking by PTW effect? What conclusions would you draw from this comparison? (14 points.)

6.Rank the locations from lowest to highest value of seasonal cycle amplitude (). Use the rankings in questions 3 and 4 to determine whether latitude or PTW explains the seasonal cycle amplitude differences between the locations. That is, does the ranking by  more closely match the ranking by latitude or the ranking by PTW effect? What conclusions would you draw from this? (12 points.)

7.Consider Kuujjuarapik, QC, along the coast of Hudson Bay. This location is at a similar latitude and elevation to Prince Rupert, and both locations are downwind of large bodies of water, but Hudson Bay is frozen during winter. Look up the climate normal data for Kuujjuarapik and complete the table below, providing the same information as provided in the table for question 2. (5 points.)

8.Compare the temperature seasonal cycle amplitude for Kuujjuarapik to that of Prince Rupert. Provide a physical explanation for any similarity or difference. (11 points.)