Currents may also be generated by density differences in water masses caused by temperature and salinity variations. These currents move water masses through the deep oceanâtaking nutrients, oxygen, and heat with them. Occasional events also trigger serious currents. Huge storms move water masses.
Ray-ban and most other manufacturers frames are made from Plastic compounds. Ray-ban used to make all its glasses out of 'glass'. Now it makes its sunglass products out of scratch resistent plastics. Often they will 'feel' like glass but are in fact most usually plastic production.
More than a half-century ago, the first modern contact lens was manufactured. It was made of a hard plastic. (The technical name is PMMA.) It rested upon the tear film of the eye. The smaller size and lighter weight of this corneal contact lens made it far more comfortable than the scleral lens.