Chapter 11 Section 2&3 Clouds and Precipitation PDF

11/20/2024 Chapter 11 Section 2 & 3 Why do atmospheric properties change with changes in altitude? 1  11/20/2...

11/20/2024 Chapter 11 Section 2 & 3 Why do atmospheric properties change with changes in altitude? 1  11/20/2024 What is the difference between stable and unstable air? Temperature Particles have more kinetic energy when they are moving faster, so the higher the temperature of a material, the faster the particles are moving. Copyright © McGraw-Hill Education Properties of the Atmosphere 2  11/20/2024 Temperature Measuring temperature Temperature can be measured in degrees Fahrenheit, degrees Celsius, or in kelvins. Copyright © McGraw-Hill Education Properties of the Atmosphere Air Pressure Air pressure is the pressure exerted on a surface by the weight of the atmosphere above the surface. The units for pressure are N/m2. Air pressure is often measured in units of millibars (mb), where 1 mb equals 100 N/m2. Copyright © McGraw-Hill Education Properties of the Atmosphere 3  11/20/2024 Air Pressure Density of air The density and pressure of the layers of the atmosphere decrease as altitude increases. Copyright © McGraw-Hill Education Properties of the Atmosphere Air Pressure Pressure-temperature-density relationship In the atmosphere, the temperature, pressure, and density of air are related to each other. Copyright © McGraw-Hill Education Properties of the Atmosphere 4  11/20/2024 Air Pressure Pressure-temperature-density relationship Temperature, pressure, and density are all related to one another. If temperature increases, but density is constant, the pressure increases. If the temperature increases and the pressure is constant, the density decreases. Copyright © McGraw-Hill Education Properties of the Atmosphere Air Pressure Temperature inversion A temperature inversion is an increase in temperature with height in an atmospheric layer. Copyright © McGraw-Hill Education Properties of the Atmosphere 5  11/20/2024 Air Pressure Temperature inversion If the land does not radiate thermal energy to the lower layers of the atmosphere, such as on a cold, clear, winter night when the air is calm, the lower layers of air become cooler than the air above them. A temperature inversion can lead to fog or low-level clouds. In some cities, a temperature inversion can worsen air-pollution problems. Copyright © McGraw-Hill Education Properties of the Atmosphere Air Pressure Wind The movement of air is commonly known as wind. In the lower atmosphere, air generally moves from regions of higher density and pressure to regions of lower density and pressure. Copyright © McGraw-Hill Education Properties of the Atmosphere 6  11/20/2024 Air Pressure Wind Near Earth’s surface, wind is constantly slowed by the friction that results from contact with surfaces including trees, buildings and hills. Higher up from Earth’s surface, air encounters less friction and wind speeds increase. Copyright © McGraw-Hill Education Properties of the Atmosphere Humidity Humidity is the amount of water vapor in the atmosphere at a given location on Earth’s surface. Copyright © McGraw-Hill Education Properties of the Atmosphere 7  11/20/2024 Humidity Relative humidity Saturation occurs when the amount of water vapor in a volume of air has reached the maximum amount possible for that temperature. The amount of water vapor in a volume of air relative to the amount of water vapor needed for that volume of air to reach saturation is called relative humidity. Copyright © McGraw-Hill Education Properties of the Atmosphere Humidity Relative humidity The dew point is the temperature to which air must be cooled at constant pressure to reach saturation. The extra thermal energy contained in water vapor compared to liquid water is called latent heat. Copyright © McGraw-Hill Education Properties of the Atmosphere 8  11/20/2024 Humidity Condensation level A process in which temperature changes without the addition or removal of thermal energy from a system is called an adiabatic process. Adiabatic heating occurs when air is compressed, and adiabatic cooling occurs when air expands. Copyright © McGraw-Hill Education Properties of the Atmosphere Humidity Condensation level At equilibrium, evaporation and condensation occur at equal rates, so the amount of water in the liquid form remains constant. Copyright © McGraw-Hill Education Properties of the Atmosphere 9  11/20/2024 Humidity Condensation level Condensation occurs at the lifted condensation level (LCL). Air above the LCL is saturated and thus cools more slowly than air below the LCL. Copyright © McGraw-Hill Education Properties of the Atmosphere Cloud Formation As a warm air mass rises, it expands and cools adiabatically. The cooling of an air mass as it rises can cause water vapor in the air mass to condense. Copyright © McGraw-Hill Education Clouds and Precipitation 10  11/20/2024 Cloud A condensation nucleus is a small particle in the atmosphere around which water droplets can form. When the number of these droplets is large enough, a cloud is visible. Copyright © McGraw-Hill Education Clouds and Precipitation Cloud Formation Atmospheric stability As an air mass rises, it cools. However, the air mass will continue to rise as long as it is warmer than the surrounding air. When an air mass sinks back to its original position and resists rising, it is considered stable. Copyright © McGraw-Hill Education Clouds and Precipitation 11  11/20/2024 Cloud Formation Atmospheric stability The stability of air masses determines the type of clouds that form and the associated weather patterns. Stable air has a tendency to resist movement. Unstable air does not resist vertical displacement. Copyright © McGraw-Hill Education Clouds and Precipitation Cloud Formation Atmospheric stability When the temperature of a mass of air is greater than the temperature of the surrounding air, the air mass rises. When the temperature of the surrounding air is greater than that of the air mass, it sinks. Copyright © McGraw-Hill Education Clouds and Precipitation 12  11/20/2024 Cloud Formation Atmospheric lifting Clouds can form when moist air rises, expands, and cools enough for water vapor to condense. Clouds can also form when air is forced upward or lifted by mechanical processes. Copyright © McGraw-Hill Education Clouds and Precipitation Cloud Formation Atmospheric lifting Orographic lifting occurs when an air mass is forced to rise over a topographic barrier. Copyright © McGraw-Hill Education Clouds and Precipitation 13  11/20/2024 Cloud Formation Atmospheric lifting Air can be lifted by convergence, which occurs when air moves into the same area from different directions and some of the air is forced upward. This process is even more pronounced when air masses at different temperatures collide. Copyright © McGraw-Hill Education Clouds and Precipitation Types of Clouds Clouds are generally classified by the altitudes at which they form and by their shapes. Copyright © McGraw-Hill Education Clouds and Precipitation 14  11/20/2024 Types of Clouds Low clouds Cumulus clouds are puffy, lumpy-looking clouds that usually occur below 2000 m. Another type of cloud that forms at heights below 2000 m is a stratus, a layered sheetlike cloud that covers much or all of the sky in a given area. Copyright © McGraw-Hill Education Clouds and Precipitation Types of Clouds Middle clouds Altocumulus and altostratus clouds form at altitudes between 2000 m and 6000 m and are made up of ice crystals and water droplets. Copyright © McGraw-Hill Education Clouds and Precipitation 15  11/20/2024 Types of Clouds High clouds High clouds, made up of ice crystals, form at heights above 6000 m where temperatures are below freezing. Some, such as cirrus clouds, often have a wispy, indistinct appearance. Copyright © McGraw-Hill Education Clouds and Precipitation Types of Clouds Vertical development clouds If the air that makes up a cumulus cloud is unstable, the cloud will continue to grow upward through middle altitudes as a towering cumulonimbus. If conditions are right, it can reach the tropopause. Copyright © McGraw-Hill Education Clouds and Precipitation 16  11/20/2024 Precipitation All forms of water that fall from clouds to the ground are precipitation. Rain, snow, sleet, and hail are the four main types of precipitation. Copyright © McGraw-Hill Education Clouds and Precipitation Precipitation Coalescence Coalescence occurs when cloud droplets collide and join together to form a larger droplet. When the droplets become too heavy to remain suspended in the cloud, they fall to Earth as precipitation. Copyright © McGraw-Hill Education Clouds and Precipitation 17  11/20/2024 Precipitation Snow, sleet, and hail The type of precipitation that reaches Earth depends on the vertical variation of temperature in the atmosphere. Copyright © McGraw-Hill Education Clouds and Precipitation Precipitation The water cycle Water moves from Earth to the atmosphere and back to Earth in the water cycle. Copyright © McGraw-Hill Education Clouds and Precipitation 18  11/20/2024 Building up the Pressure 1. Part one – Pressure and temperature 1. Collect all material 1. Part one – Pressure and temperature 2. Add colored water to bottle 1. Two Graphs and tables 3. Cut straw and add cm 2. Questions 4. Add straw to bottle 1. Give a general statement about your 5. Seal bottle with clay observations? 6. Measure and graph 1. Measure water height 2. What relation could you make with 1. Measurements only 1 min temperature and pressure? Why? 2. Add Ice cube around tube 1. Measure height for 5 min 2. Graph 2. Part Two – Make them Clouds 1. Collect large bottle and fill 1/3 with hot water 2. Part Two – Make them Clouds 2. Add food coloring 1. Draw the model 3. Close lid lightly 2. Questions 1. Document observation 1. What does this model represent and is it 4. Add Ice on top of lid 1. Document observations accurate? 2. What features could improve the model? 19