Labels:convex polyhedron | crt screen | lemon | monitor | sky | tv OCR: SPH ER E The outermost or topmost, portion of the atmosphere Its lower boundary is the critical level escape variousi estimated 500 1000 m above the Earth's surface. Also called region of escape because high Exosphere velocity atoms and molecules continually escape the gravity Thermosphere lonosphere Mesospherc Stratosphere Ozone Troposphere Mesosphere