International Symposium on
Drylands Ecology and Human Security
Analysis of some Meteorological Factors Affecting Rainfall
Sawalha, A.; Salhut, S. and Sbeih, M and Kanan, A
Al Quds University – Palestine
Drought periods and rainfall fluctuation are the most natural factor affecting the environmental vulnerability in Palestine. Water resource availability depends on the volume, distribution and intensity of precipitation during the six months of rainy season, which will prevail from November until March. The amount of rainfall is a key factor in developing the agricultural sector especially is rain fed crops. Meteorological data at Al Quds University weather station were collected during the last five years with a time interval of one hour. Backward Method was used to analyze any possible changes in meteorological factors (air temperature, air pressure, relative humidity, wind speed, wind direction and solar radiation) affect precipitation. We found out that changes in relative humidity and air pressure during any given 48 hours previous to actual rainfall are strongly correlated with the possibility of rainfall occurrence. The other variables have a less notable effect.
We used the Cross Tabulation method to investigate the relation between rainy day followed by rainy or non rainy day, the result of this assumption is: a day without rainfall in September-October have the probability of 86% to follow with non rainy day. On the other hand, there is probability of 14% of having a rainy day. These percentages change during winter months, after a rainy day the probability increases to 54% to have more rain.
A linear regression analysis of rainfall was conducted to evaluate the relationship between number of rainfall events in a month and the precipitation amount. It was found that the two variables are linearly related with correlation of 87.2% and the volume of rainfall depends on the number of the rainfall events and not on the amount of measured precipitation of each event.