1st Secondary Grade Integrated Science - Chapter 2 Atmosphere PDF

Integrated Science st TheII 1 Secondary Grade Chapter 2 Atmosphere Lesson 1 : Atmosphere, its layers and components What happens if a planet has no atmosphere? Mercury, the...

Integrated Science st TheII 1 Secondary Grade Chapter 2 Atmosphere Lesson 1 : Atmosphere, its layers and components What happens if a planet has no atmosphere? Mercury, the smallest planet of the solar system, does not have a gas envelope, so the surface of the planet absorbs the solar radiation that falls on it, so the temperature of the planet rises greatly, and when the sun is absent with its cycle, the radiation is emitted from the planet into space, and it cools very quickly because there is no gas envelope that retains the radiation. The atmosphere is a layer of gases that surrounds the planet Earth and protects it from most of the radiation and objects coming from space and maintains the balance of temperatures on its surface. The atmosphere contains gaseous components that support the existence of life. Earth's gravity keeps the Earth's atmosphere in place. In this chapter, we will learn about the composition of the atmosphere, its main components, and the effect of these components on the sustainability of life on Earth. The atmosphere is composed of a mixture of several gases, the most important of which are: - Nitrogen (N2): represents about 78% of the volume of the atmosphere, and it is a largely inert gas that does not easily react with other gases and elements, and needs special conditions such as lightning or very high temperatures to react, so its oxides are very small in the air. - Oxygen (O2): represents about 21% of the volume of the atmosphere and is an essential gas in the respiration process of all living things. O2 is chemically active. It is the active element in combustion, the respiration of living organisms, and many natural and industrial chemical reactions. 01063200774 40 ENG / Mahmoud FATHY  Integrated Science st TheII 1 Secondary Grade - Argon (Ar): an inert gas that makes up about 0.93% of the volume of the atmosphere. - Carbon dioxide (CO2): Makes up about 0.04% of the volume of the atmosphere and is essential for plant photosynthesis. - Water vapor (H2O): Its percentage varies from one place to another in the near layer of the atmosphere, and it plays an important role in weather and climate phenomena. - Ozone gas (O3): The ozone layer is found at an altitude of approximately 10 km - 55 km from The Earth's surface, and is characterized by its ability to absorb short-wave ultraviolet radiation, thus protecting living organisms on the surface of Earth from its destructive effect, while Ozone The Earth's surface is toxic and harmful to these organisms Layers of the atmosphere: The atmosphere is divided into several layers, each of have special characteristics, the most important of which are : ① Troposphere : The layer closest to The Earth's surface, with a thickness of about 18 km at the equator and 8 km at the two poles. It is thicker at the equator due to the presence of hot convection currents that push gases upward. The air temperature decreases with height in that layer, reduced by one degree Celsius for every 176 m. This decrease in temperature is due to the decrease in atmospheric pressure with altitude, which leads to the expansion of the air, which requires energy from some of the kinetic energy of the air molecules. In this layer, many weather phenomena related to weather and climate occur, such as cloud formation, rainfall, wind movement, etc. ② Stratosphere: The layer above the troposphere, its height up to 50 km above sea level, contains the ozone layer. The temperature does not change through the stratosphere layer until an altitude of 20 km, then the temperature starts to rise as we go higher due to the presence of ozone gas in the upper part of the stratosphere. Air movement is horizontal, so this layer is preferred for airplane flights. 01063200774 41 ENG / Mahmoud FATHY  Integrated Science st TheII 1 Secondary Grade ③ Mesosphere: A layer about 30 km thick is the lowest layer of the atmosphere with the lowest temperature (-90 oC). Most meteors falling from space burn up as they pass through this layer, which protects the Earth from them. ④ Ionosphere Extending approximately to 640 km above sea level, it is an electrically charged layer as a result of ionization of atmospheric atoms due to solar radiation, so it is used in long-distance radio communications due to its ability to reflect radio waves. The effect of atmospheric pressure on wind movement Atmospheric pressure is the result of the weight of the column of air extending from a given point to the end of the atmosphere and affecting the unit area around it. Atmospheric pressure varies from one point to another in the atmosphere, as the value of atmospheric pressure is affected by the height of the air column above the point. This difference in atmospheric pressure between two areas in the same horizontal plane leads to the movement of air from the area with high atmospheric pressure to the area with low atmospheric pressure. On weather maps, lines are drawn connecting all places or points with equal atmospheric pressure called isobars, with low barometric pressure symbolized by the letter 'L' and high atmospheric pressure symbolized by the letter 'H'. The millibar is usually used as the unit of barometric pressure on meteorological maps. 01063200774 42 ENG / Mahmoud FATHY  Integrated Science st TheII 1 Secondary Grade Mercury barometer A mercury barometer is used to measure atmospheric pressure. Activity: In the figure, a mercury barometer has a vertical height difference between the two mercury levels of 760 mm, discuss with your partner: - Why is this height representative of atmospheric pressure? - How can the barometer be used to determine the height of a mountain, for example Standard (normal) atmospheric pressure: The value of atmospheric pressure at sea level at 0 degrees Celsius is called the standard (normal) atmospheric pressure and is equal to 101300 N/m2, which is equivalent to 1013 millibar, or 760 mm.Hg. 01063200774 43 ENG / Mahmoud FATHY