Objective: Pressure caused by the weight of the atmosphere. Blanket (Layer) of gases surrounding a planet

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1 1 Objective: You will understand upon completion that: The atmosphere is composed of layers that vary in properties The atmosphere has a specific composition based on a mixture of gases The atmosphere's pressure varies based on distance form Earth The atmosphere's layers are divided by temperature in differences Let s see if you know more than what you thought!!! Which statement is true about the role of the atmosphere? 1. Keeps us from floating into space. 2. Keeps us the right temperature to sustain life. 3. The percentage of water vapor never varies. Concept/Vocabulary Air Pressure Altitude Atmosphere Exosphere Mesosphere Stratosphere Thermosphere Troposphere Word Definition Pressure caused by the weight of the atmosphere Height Blanket (Layer) of gases surrounding a planet The 5 th layer that extends into outer space The 3 rd layer containing where meteorites burn up The 2 nd layer containing the ozone layer The 4 th layer that also contains the ionosphere The 1 st layer containing 80% of the atmosphere's mass Earth s Changing Atmosphere 1.1 Earth s Atmosphere Supports Life Atmosphere makes life on Earth possible

2 2 Atmosphere - Living things use in the air, plants use in the air The atmosphere keeps Earth The atmosphere protects life A. Characteristics of the Atmosphere Altitude Altitudes above can be called outer space Density or (The amount of mass in a given volume of air) If there are more molecules in a given volume, the density is greater. If there are fewer molecules, the density is less. Pressure The force pushing on an area or surface is known as. The weight of the atmosphere exerts a force on surfaces. is the result of the weight of a column of air pushing down on an area. The column of air extends upward through the entire atmosphere, as shown in Figure 4. The atmosphere is heavy. The weight of the column of air above your desk is about the same as the weight of a large school bus. So why doesn t air pressure crush your desk? The reason is that the molecules in air push in all directions down, up, and sideways. The air pushing down on top of your desk is balanced by the air pushing up on the bottom of your desk. Ex: As you travel, density A breath of air on a mountain has than a breath of air at sea level Most of the mass of the Earth s atmosphere is

3 Altitude Also Affects Density As you go up through the atmosphere, the density of the air. This means the gas molecules that make up the atmosphere are at high altitudes than they are at sea level. If you were near the top of a tall mountain and tried to run, you would quickly get out of breath. Why? The air contains 21 percent oxygen, whether you are at sea level or on top of a mountain. However, since the air is dense at a high altitude, there are oxygen molecules to breathe in each cubic meter of air than at sea level. So you would become quickly at altitudes. 3 Measuring Air Pressure textbook ch1, sect 2 A is an instrument that is used to measure air pressure. Two common kinds of are and. Units of Air Pressure Weather reports use several different units for air pressure. Most weather reports for the general public use of mercury. For example, if the column of mercury in a mercury barometer is 30 high, the air pressure is 30 of mercury or just 30 inches. B. Materials in the Atmosphere Percentages of Gases In Dry Air The atmosphere s gases provide materials essential for living things. promotes and is an important ingredient in that make up living things Oxygen is necessary for and to perform life processes is used by to make food II. Natural Process Modify the Atmosphere A. Ongoing Processes Each day, you breathe in and out about of air

4 The air you inhale is from the air you inhale B. Cycle - _ 1. The Carbon Cycle Along with the nitrogen cycle and the water cycle, the carbon cycle comprises a sequence of events that are key to making the Earth capable of life; it describes the movement of carbon as it is recycled and reused throughout the biosphere. All living organisms are based on the carbon atom. Example: o o 4 2. The Nitrogen Cycle Example:

5 o o o o 5 Nitrogen circulates through Earth s environment in several forms. Nitrogen is essential to life on Earth. Seventy-eight percent (78%) of the Earth s atmosphere is nitrogen gas. But most of this nitrogen is not usable by life on Earth. Microscopic organisms called microbes transform nitrogen into a form usable by plants. The plants, in turn, supply nitrogen for animals. Nitrogen fixation is a process in which special bacteria and blue green algae change nitrogen gas into certain nitrogen compounds. Lightning, ultraviolet radiation and electrical equipment can fixate nitrogen. Algae and other more complex plants use nitrates and ammonia created by nitrogen fixation. Animals eat these plants and use the nitrates in their bodies. The remains of dead plants and animals are decomposed, creating ammonia. This ammonia is a turned back into nitrate by bacteria through a process called nitrification. In watery soils, bacteria use nitrates and nitrogen gas is formed. 3. The Water Cycle Example:

6 o o o 6 Earth's water is always, and the natural water cycle, also known as the cycle, describes the continuous movement of water,, and the surface of the Earth. Water is always changing between,, and, with these processes happening in the blink of an eye and over millions of years. C. Sudden Changes can affect the atmosphere, such as: o - o - o -