Variation In Surface Water Vapour Density Over Four Nigerian Stations

The surface water vapour density ρ has been studied using monthly averages of temperature and relative humidity at four selected weather stations in Nigeria for the years 1987 to 1991. It is found that during the dry season months of November to March, ρ is higher at night by an average of about 9.9% than during the day at Ikeja, Ibadan, and Ilorin whereas during the rainy season months of April to October, the daytime values of are higher in these stations. On the other hand, at Minna, at night is generally lower by an average of about 5% than daytime values during the two seasons of the year. Annual double peaks occur at Ikeja, Ibadan and Ilorin signifying respectively the beginning and the end of the rainy season in these stations. At Minna, a single maximum of about 20.89±0.3g/m3 prevails between May and September, while the minimum of about 6.8±1.3g/m3 occurs in January. Key words: Vapour density, intertropical discontinuity, dry season, rainy season, relative humidity Nig. J. of Pure & Appl. Physics Vol.3 2004: 38-4