We compared our data and were surprised to discover ISD's leaves changed color earlier (prior to 11/4) than MSSD's (well after 11/7). Our schools have similar latitudes, so we expected the colors to change about the same date. Maybe they were different because ISD is inland, and MSSD is close to the Chesapeake Bay and the Atlantic Ocean. MSSD's fall climate may be milder because of the effect of large bodies of water nearby. The temperature graphs show the average temperature Oct 8-Nov 8 is a few degrees lower in Indiana. Indiana's is around 10 degrees C and Washington, D.C's is around 12 degrees C. The first differences we noticed between our schools are the average temperatures and the timing of leaf fall.

The temperature graphs show daily variations, but generally show a decrease during the fall for both schools. ISD and MSSD's graphs show a warm day the end of November. In Indiana, the temperature increase appeared on the 312th day, and then MSSD's also increased on the 314th day. This may exhibit air masses moving from west to east.

The precipitation graphs are episodic, having no changes and then one day it soars high. ISD and MSSD had similar precipitation patterns. Weather prior to the reflectance study was dry, especially in Indiana. Large amounts of rain (12 and 13.3 mm) were recorded October 21 and October 29. We suspect increases in IR reflectances correspond to increases in precipitation; when the precipitation increases, IR reflectance increases. ISD's IR-1 wavelength soared on the 303rd day, the day after a very large rainfall, and MSSD's IR follows that pattern. At MSSD, some of our students studied IR and precipitation carefully last spring and they found this correlation. We think our data shows it too.

MSSD's graph for blue wavelength shows an increase. In the blue spectral region, several factors influence leaf reflectance, including chlorophyll and the leaf's cuticle. The greater the amount of the chlorophyll that is present, the greater the absorption of blue will be. In Indiana's graph, blue wavelength data is low and steady, and does not show much variation. That surprised us because the blue reflectance is considered a helper for photosynthesis. Our hypothesis suggested that the blue wavelength would stay the same. However, MSSD's blue increases during the fall, which is not explained by our hypothesis. Now that we've learned more, it makes sense that the blue wavelength would increase. We asked Dr. Barry Rock about this. He pointed out that when there is less chlorophyll, the blue is not absorbed, so it will be reflected. That could explain MSSD's data, but we still have questions about why ISD's blue wavelength did not seem to increase. We learned that the leaf's cuticle affects the blue wavelength. The thicker the cuticle is, the greater the % reflectance in blue will be. We are wondering if ISD's Sugar Maple leaves have a thinner cuticle as the chlorophyll disappears, which might account for ISD's blue reflectance.

The % reflectance for the color of green decreased on MSSD's graph. The photosynthesis started to slow, because the tree began to pull in chlorophyll, now that it is winter. ISD's green graph showed about a 14% increase in reflectance.

We expected the yellow wavelength to be unchanging, since carotenoids are always present in the leaf, and when chlorophyll breaks down the yellows appear. The data from both schools shows yellow reflectance increased during autumn. We were not able to figure out an explanation for that. We know that the color of MSSD's and ISD's Maple leaves was green and later changed to yellow. We did not see red color, but Indiana found a 21% increase in the crimson trend during that time. They also had a 16% increase in the red region. MSSD's reds show an overall increase, too. We read that leaves start to produce anthocyanins in the fall, which could explain the increases in the red wavelengths. This is what our hypothesis predicted we would find.