Layers of the Atmosphere (pages 16 21) Introduction (pages 16 17) Key Concept: Scientists divide Earth s atmosphere into four main layers classified according to changes in temperature These layers are the troposphere, the stratosphere, the mesosphere, and the thermosphere Scientists divide the atmosphere into four layers They classify these layers by the changes in temperature As you go from one layer to the next, the temperature changes in a different way The troposphere is the lowest layer of the The stratosphere is the second layer as you go up The mesosphere is the third layer as you go up The thermosphere is the top layer 1 In the picture below, fill in the blanks Altitude (km) 120 100 80 60 40 20 0 Thermosphere b Stratosphere a 11
2 Is the following sentence true or false? Scientists divide the atmosphere into layers based on thickness The Troposphere (page 18) Key Concept: The troposphere is the layer of the atmosphere in which Earth s weather occurs You live in the troposphere (TROH puh sfeer) It is the lowest layer of the Most weather happens in the troposphere For example, when it is raining, it is raining in the troposphere The troposphere contains almost all of the mass of the In the troposphere, the temperature decreases as the altitude increases In other words, the higher you go in the troposphere, the colder it gets 3 Circle the letter of each sentence that is true about the troposphere a The troposphere is the lowest layer of the b Most weather happens in the troposphere c The troposphere contains almost no mass 4 Is the following sentence true or false? In the troposphere, the temperature increases as the altitude increases 12
The Stratosphere (page 19) Key Concept: The stratosphere is the second layer of the atmosphere and contains the ozone layer The stratosphere is the layer of the atmosphere just above the troposphere It is just below the mesosphere The middle portion of the stratosphere contains the ozone layer The ozone layer is where there is more ozone than in any other part of the The ozone layer blocks harmful energy from the sun In the stratosphere, the temperature increases as the altitude increases In other words, the higher you go in the stratosphere, the warmer it gets 5 The layer just above the troposphere is the 6 Circle the letter of each sentence that is true about the stratosphere a The stratosphere is just below the thermosphere b The middle portion of the stratosphere contains the ozone layer c The higher you go in the stratosphere, the warmer it gets 7 Is the following sentence true or false? In the stratosphere, the temperature decreases as the altitude increases 13
The Mesosphere (page 20) Key Concept: The mesosphere is the layer of the atmosphere that protects Earth s surface from being hit by most meteoroids The mesosphere is the layer of the atmosphere just above the stratosphere In the mesosphere, the temperature decreases as the altitude increases So, the higher you go in the mesosphere, the colder it gets A meteoroid is a chunk of rock or metal from space Most meteoroids heading toward Earth burn up in the mesosphere 8 Circle the letter of each sentence that is true about the mesosphere a Most meteoroids heading toward Earth burn up in the mesosphere b In the mesosphere, the temperature decreases as the altitude increases c The mesosphere is the layer just above the thermosphere 9 A chunk of rock or metal from space is a(n) The Thermosphere (pages 20 21) Key Concept: The outermost layer of Earth s atmosphere is the thermosphere The top layer of the atmosphere is the thermosphere It is above the mesosphere 14
In the thermosphere, the temperature increases as the altitude increases So, the higher you go in the thermosphere, the higher the temperature is The thermosphere is divided into two layers The lower layer of the thermosphere is called the ionosphere (eye AHN uh sfeer) The colorful displays called the Northern Lights take place in the ionosphere The outer layer of the thermosphere is called the exosphere The exosphere gradually blends with outer space ideas on page 14 and above 10 Circle the letter of each sentence that is true about the thermosphere a The thermosphere is divided into two layers b In the thermosphere, the temperature increases as the altitude increases c The thermosphere is the top layer of the 11 Read each word in the box In each sentence below, fill in one of the words exosphere mesosphere ionosphere a The Northern Lights take place in the b The gradually blends with outer space 15