As stated in the text, solar flux often varied considerably between the locations of Maize & Blue and Scout in Sunrayce 93. However, most of the time, the difference was not too great. Below is a description of the relative locations of Maize & Blue and Scout along the race route, focusing on times during which this difference may have caused significant differences in solar flux over periods of greater than several minutes. Reference to figures 12-17 (12 13 14 15 16 17) and 6-11 (6 7 8 9 10 11) is helpful here.

From Arlington to Whitesboro, Scout generally stayed 15-25 km (about 15-25 min.) ahead of Maize & Blue. This should not matter significantly regarding solar flux, since the cloudiness was fairly uniform throughout most of the morning. Maize & Blue arrived at the media stop about 25 min. after us, thus only saw little of the clearing we experienced from 1020-1040. They probably saw few, if any, GSR readings of over 400 W/mē until the afternoon.

At Whitesboro, Scout pulled ahead of the caravan quickly. Maize & Blue most likely did not see the heavier drizzle showers we saw in Scout, as they seemed to be moving from a general easterly direction and probably cleared the route before Maize & Blue arrived. However, Maize & Blue did not see the clearing as early as we did also. Still, the clearing was at least as much due to the diurnal cycle as to the intrusion of dry air, so they probably saw similar conditions to us by 1230. We finished 40 km (40 min.) ahead of Maize & Blue.

Scout began the day 25 km ahead of Maize & Blue, and then let them catch up as clearing began to occur. From 0815-0845, Scout sat under many clouds when it was clearer in the vicinity. Thus, our GSR readings are lower than what is representative for that time. From then, we got about 20 km (20 min.) ahead of Maize & Blue by Shawnee. Thus, Maize & Blue should have experienced both the clearing and subsequent cloudiness slightly later than Scout.

After the media stop, Scout went out fast to see if any clearing was to be expected soon. So we got 30 km (35 min.) ahead of Maize & Blue by 1120. We sat under a dark area of clouds from 1130-1145, waiting for Maize & Blue to arrive so that we could compare GSR and array power readings, which we did from 1150-1205. Afterward, we speeded up to reach the Tulsa Fairgrounds about 30 km (45 min., due to city traffic) ahead of Maize & Blue. Maize & Blue should have experienced similar solar fluxes as Scout in the afternoon, with slightly lower amounts from 1205-1245, since we were further into the clearing, and somewhat higher ones until Maize & Blue arrived in Tulsa, where it was cloudier.

Scout started out 10 mi. ahead of Maize & Blue. However, as Cu rapidly developed after 0800, we let Maize & Blue catch up to see what they were under. Thus, we were stopped from 0820-0835. For the first 10 min., we were under a large, developing Cu, so that our readings are actually likely to be lower than those at Maize & Blue then. After this, ours were higher until 0920, since it was clearer further down the route (especially earlier in the period). By 0920, the sky cover was much less, such that location did not matter so much. We stayed about 15 km (15 min.) ahead of Maize & Blue to Miami, so experienced the increase in cloudiness there slightly earlier than Maize & Blue.

Scout left Miami fairly quickly to get ahead of Maize & Blue, which is not that difficult to do at 100 km/h, so we probably saw slightly clearer conditions for the first 20-30 min. Skies once again became mostly clear, such that location did not matter so much. We let Maize & Blue pass us once for reconnaissance purposes, and then got about 40 km (35 min.) ahead by the finish. Thus, we saw the cirroform clouds somewhat earlier in the afternoon than Maize & Blue.

Scout went out very fast on this day to see how conditions were developing to the N and W. Thus, we were 50-65 km ahead of Maize & Blue by 0915. We then drove back to let Maize & Blue catch up. Since we were going into thicker Cs, Maize & Blue most likely saw higher solar fluxes than us throughout most of the morning. As we headed into Kansas City, we once again got ahead of Maize & Blue; this time by about 15 km (25 min., due to city traffic). Location did not matter as much in this case, since the cloudiness (actually, lack of it) was fairly uniform at this time and place.

After the media stop, Cu clouds quickly moved in and developed before Scout had a chance to get ahead of Maize & Blue. Thus, the solar flux amounts should be similar once again, with local variations due to variability in darkness of convective clouds and the few breaks in them. We generally stayed 8-15 km ahead of Maize & Blue in the afternoon, but were within 3 km ahead of Maize & Blue for the last 25 km (35 min.) of racing.

Scout started out about 15 km ahead of Maize & Blue, and quickly got 30 km ahead, since racing was slow. Chase called to say it was getting brighter and that Maize & Blue was occasionally getting over 500 W of array power around 0840. Thus, we went back and then waited briefly for Maize & Blue to catch up, and then continued about 15 km (25 min.) ahead. Even though the whole weather system moved in from the WNW, the variations in cloudiness were very uniform in a N-S direction, judging from the times we went back and forth on the route. The early morning brightening that Maize & Blue experienced was short-lived, and for the remainder of the way to Lineville, there was generally about a 25 min. lag between the fluxes Scout and Maize & Blue experienced.

Starting out from Lineville, we were under very dark skies, especially considering that it was near solar noon and that there was not much rain. After a while, some brightness appeared to the NW, so at 1220, we went out to investigate. Thus, by 1300 we were about 60 km ahead of Maize & Blue. When we returned to catch up with Maize & Blue, we ran into periods of heavy rain at until about 1330. We were very close to Maize & Blue until 1430, at which time we headed out toward Des Moines. We got to Des Moines at 1600, and waited about an hour there, so we were about 30 km ahead of Maize & Blue at that time. Maize & Blue reached us at 1710, and we headed into the Iowa State Fairgrounds just ahead of them. Thus, there were most likely several discrepancies between solar fluxes experienced by Scout and Maize & Blue. Their amounts were probably lower than ours from 1200-1230, and definitely lower from 1430-1600. However, the clearing moved in from the WNW and the Ac clouds were dissipating, so the time lag in the development of late afternoon clearing is questionable.

Scout started out 15 mi. ahead of Maize & Blue. At mile 20 (about 32.2 km from the start), we let Maize & Blue catch up, as we were timing competitors. Then we got ahead again. This all did not matter much regarding solar flux, since there was no cloud shadowing to Iowa Falls. Actually, it was kind of surprising to me that this was the only one of 13 major stretches along the route that was clear.

Starting out from Iowa Falls, all Cu were distant to the NE-NW and small. However, they started to develop to the NW and drift over the route. As mentioned in the text, Scout did an outstanding job at avoiding any cloud shadowing until 1252, but Maize & Blue, being about 20 km behind, probably saw their first shadowing earlier! From 1300 until reaching Albert Lea, there was significant Cu cover. Since we finished about 40 km (40 min.) ahead of Maize & Blue, there was an average time lag of about 30 min. between our conditions and theirs.

Text and embedded images are copyright of Joseph Bartlo, though may be used with proper crediting.