Matsuyama plain has an obvious contrast of land use in urban and rural area. The purpose of this study is to investigate the effects of differences in land use on the formation of clouds, using the summer time datasets from the observations of cloud base level, solar radiation, surface heat flux, air temperature and humidity. The followings are main outcomes. Cloud base level over urban area was higher than that over rural area when wind blew along the border of the abrupt change of land use. Solar radiation over urban area tended to be smaller than that over rural area in the afternoon of days with a percentage of sunshine ranging from 50% to 80%. This was demonstrated by the development of mixing layer estimated from surface heat flux.