Simplify the following text for a Grade 8 native English-speaking person.
Original: Wind shear affects sailboats in motion by presenting a different wind speed and direction at different heights along the mast . The effect of low level wind shear can be factored into the selection of sail twist in the sail design , but this can be difficult to predict since wind shear may vary widely in different weather conditions .
Simplified: Wind shear can be divided into two different types : horiztontal and vertical wind shear .