Why there are no rainforests in northern Africa?

couse of the winds they are blowing from center of africa on north and south in upper level and then in the lower level second type of winds are blowing to the center and the clouds (with rain) so only in the center of africa it is raining (everyday) and there is no rain on north and on south from it. I`m not english so it is hard for me to translate the definition which was given on my geo lessons into english 8)