Science

• Our earth is surrounded by a blanket of air known as the atmosphere.
• The atmosphere is made up of a mixture of gases.
• Our atmosphere can be divided into five layers : troposphere, stratosphere, mesospher, thermosphere and exosphere.
• We live in the troposphere, the layer closest to the ground.
• It is about 10 km in heigh and contains 75% of the atmospheric gases. Weather occurs here because this layer contains most of the water vapor.
• The stratosphere extends to the height of 50 km. There is no cloud here and the air is stil.
• Most planes fly in the stratosphere.
• The stratosphere contains a thin layer of ozone.
• The ozone layer absorbs the harmful ultraviolet rays from the sun. These rays cause sunburn and skin cancer.