ICE - frozen water
                                                
INFILTRATION - the process by which water seeps into the soil
                                                                  
ION - one of the electrically charged particles in certain substances; an atom or group of atoms that has a negative or positive electric charge
                                                                                 
IONIC - having ions
                                                                                                  
IONOSPHERE - an ionized region of the upper atmosphere, able to reflect radio waves for transmission to another part of the earth
                                                                                                               
IRRIGATION - to water by way of canals, ditches or pipe