Multiple Correspondence Analysis characterizing 1-and 8-hour ozone concentrations in relation to climate parameters, Tours, August 2003. This graph was plotted with 744 statistical units (24 hours per day × 31 days × 1 month). Active variables are meteorological parameters: temperature (T, blue cross), relative humidity (RH, green bold square), sunshine (S, brown bold circle), atmospheric pressure (P, black cross), wind speed (WS, blue bold triangle) and wind direction (grey bold triangle). Illustrative variables are 1- (red square) and 8-hour ozone concentrations (red rhombus) (1h-O3 and 8h-O3 respectively). The proportion of the global variance expressed by F1 and F2 is indicated in italics. The indices beside each symbol refer the intensity from 1, the lowest values to the highest values.