Assessment / Application Exercises

Three sets of observations were collected on the same day: May 6, 2006. These observations were from Miami, FL; Phoenix, AZ; and International Falls, MN. Compare the observations between any two of these three cities. In your comparison:

• note if the patterns of temperature, dewpoint, and relative humidity are similar or different between the stations
• note which stations have more moisture and which have less moisture
• note which stations were warmer or cooler

If you choose the following pairs of cities, consider these questions:

• Phoenix & International Falls: Both cities measured the same the dewpoint values at 10:00 a.m. local time. Were the relative humidity values at 10:00 a.m. the same at both cities? Why or why not?
• Phoenix & Miami: Both cities measured similar maximum temperatures. To the human body, which location "felt" warmer? Why?
• Miami and International Falls: Both cities measured similar minimum relative humidity values (within 5% of each other). Does this mean both cities had the similar amounts of water vapor in the air? Why or why not?

Phoenix and International Falls:

The patterns are similar between the stations: temperature decrease before sunrise, rises between sunrise and mid-afternoon and decreases after that. In general, the dewpoint changes much less than the temperature, and the relative humidity trends are mirror-images of the temperature traces.

The dewpoint at Phoenix stays between 30 and 37 degrees (starts at 35 and ends near 30). At International Falls, it starts at 30 and rises to 38. The moisture content at the two stations is near the same, although Phoenix starts with a bit more moisture than International Falls, and International Falls ends with more moisture than Phoenix.

Phoenix was much warmer than International Falls. The temperature at Phoenix ranged between 67 and 89 while International Falls was between 37 and 61. The high at International Falls was colder than the low temperature at Phoenix.

At 10:00 a.m., the dewpoint values were 36. The relative humidity values were 20% at Phoenix and 52% at International Falls. This is because the temperature was so much warmer at Phoenix.

Phoenix and Miami:

The patterns are similar between the stations: temperature decrease before sunrise, rises between sunrise and mid-afternoon and decreases after that. In general, the dewpoint changes much less than the temperature, and the relative humidity trends are mirror-images of the temperature traces.

The dewpoint at Phoenix stays between 30 and 37 degrees (starts at 35 and ends near 30). At Miami, it starts and ends at 64 with several 2 or 3 degree fluctuations during the day. Thus, Miami with a larger dewpoint, has significantly more moisture than Phoenix.

The temperatures at the two locations were similar. The temperature at Phoenix ranged between 67 and 89 while Miami was between 71 and 89.

Phoenix measured its maximum of 89 between 1:00 and 4:00 p.m., when the relative humidity values were about 15%. Miami measured its maximum temperature of 89 at 3:00 p.m, with a corresponding relative humidity of 40%. Looking at the heat index chart, a temperature of 90 and RH of 15 feels like 86 (Phoenix), while a temperature of 90 and RH of 40 feels like 91, so Miami would feel slightly warmer.

Miami and International Falls:

The patterns are similar between the stations: temperature rises between sunrise and mid-afternoon and decreases after that. In general, the dewpoint changes much less than the temperature, and the relative humidity trends are mirror-images of the temperature traces.

The dewpoint at Miami starts and ends at 64 with several 2 or 3 degree fluctuations during the day. At International Falls, it starts at 30 and rises to 38. Thus, Miami with a larger dewpoint, has significantly more moisture than International Falls.

Miami was much warmer than International Falls. The temperature at Phoenix ranged between 71 and 89 while International Falls was between 37 and 61. The high at International Falls was colder than the low temperature at Miami.

Miami measured its minimum relative humidity (40%) at 4:00 p.m. The temperature and dewpoint at the time were 88 and 61, respectively. The minimum relative humidity at International Falls was 38%, observed at 5:00 p.m. The temperature and dewpoint at International Falls at 5:00 p.m. were 60 and 34, respectively. Because the dewpoint was much greater at Miami, it has more moisture than International Falls. The RH values are similar because there is a similar spread between temperature and dewpoint (over 26 to 27 degrees).

Station: KPHX -- Phoenix, AZ

Latitude: 33.4342 = 33 degrees 26 minutes 3 seconds North

Longitude: -112.0511 = 112 degrees 3 minutes 3 seconds West

Station: KMIA -- Miami, FL

Latitude: 25.7906 = 25 degrees 47 minutes 26 seconds North

Longitude: -80.3164 = 80 degrees 18 minutes 59 seconds West

Station: KINL -- International Falls, MN

Latitude: 48.5619 = 48 degrees 33 minutes 42 seconds North

Longitude: -93.3978 = 93 degrees 23 minutes 52 seconds West