[t yr mo day rad] = textread('Ohare_Solar.txt','%d%d%d%d%f','headerlines',1);
figure(1);
histogram(rad,'BinWidth',25);
xlabel('Radiation (Wh/m^2)');
ylabel('# of Days');
title('Full Year Histrogram of Solar Radiation Levels');

may = find(mo == 5);
may_rad = rad(may);
figure(2);
histogram(may_rad,'BinWidth',25);
xlabel('Radiation (Wh/m^2)');
ylabel('# of Days');
title('Figure 3.7: Histrogram of Solar Radiation Levels in May 2005');