Assignment 5 - Reading questions with answers PDF

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Morgan Walsh GHP 100P-01 September 28, 2020 Assignment 5 Concept Checks 5.1 Describe the process of cloud formation. For condensation to generate clouds, the air must reach saturation, and there must be a surface on which the water vapor can condense to form liquid droplets. What role do cloud condensation nuclei play in the formation of clouds? Cloud droplet growth begins on cloud condensation nuclei. Why isn’t condensation alone able to generate droplets large enough to fall as rain? Even in extremely moist air, the growth of cloud droplets by additional condensation is very slow. The size difference between clouds droplets and raindrops is also very distinct- it takes about 1 million cloud droplets to form a single raindrop. Because of this, condensation is not the cause for the formation of raindrops large enough to fall to the ground without evaporating. Eye On The Atmosphere 5.1 1. Describe how these clouds form, based on the term orographic clouds. Orographic clouds develop in response to forced lifting of air by earth’s topography, in this case a mountain. 2. Why does this cloud have a relatively flat bottom? This cloud formed as the air near the ground rose. The temperature and dew point temperature near the ground are relatively uniform, so as a layer of air near the ground rises, the height at which condensation occurs does not vary much and the base of the cloud is flat. 3. Cap clouds are related to another cloud type having a very similar shape. Can you name the cloud type? Lenticular clouds. Concept Checks 5.2 What are the two criteria by which clouds are classified?

Clouds are classified by form and height. Why are high clouds always thin in comparison to low and middle clouds? They have low temperatures and small quantities of water vapor present at high altitudes, resulting in high clouds that are thin, white, and made up mostly of ice crystals. List the 10 basic cloud types, and describe each based on its form (shape) and height (altitude). Cirrus clouds are thin and high. Cirrocumulus clouds are thin and high. Cirrostratus clouds are thin and high. Altocumulus clouds are middle clouds, often made of separate globules. Altostratus clouds are thin middle clouds. Stratus clouds are uniform, low clouds that resemble fog. Stratocumulus clouds are low clouds in globular patches or rolls. Nimbostratus clouds are thick, dark grey, low clouds. Cumulus clouds are dense, billowy, low clouds. Cumulonimbus clouds are low, towering clouds. Concept Checks 5.3 Distinguish between clouds and fog. Clouds result when air rises and cools adiabatically, fog results from cooling or when air becomes saturated through the addition of water vapor rather than the changes in pressure that cool rising air. List five types of fog and discuss how they form. Radiation fog is formed by cooling. Advection fog is formed by cooling. Upslope fog is formed by cooling. Steam fog is formed by the addition of water vapor. Frontal (precipitation) fog is formed by the addition of water vapor. What actually happens when a radiation fog “lifts”? As the Sun warms the ground, the lowest layer of air is heated first, and the fog evaporates from the bottom up. Eye On The Atmosphere 5.2 1. Why do you think the clouds formed over the ocean while the land areas are cloud free? The evaporation from water forms clouds more quickly than evaporation from land. 2. Why are the mountainous areas of western Washington State covered with lush vegetation while much of the eastern half of the state appears semiarid?

The mountainous areas are higher in altitude, allowing them to absorb water from low clouds that then enriches the vegetation. Concept Checks 5.4 Describe the Bergeron process. The Bergeron process occurs in cold clouds, where water vapor is deposited on ice crystals, lowering the relative humidity of the air. This causes the surrounding water droplets to evaporate and replenish the lost water vapor. Explain how snow that formed high in a towering cloud might produce rain. When the surface temperature is above 4 degrees Celsius, snowflakes usually melt before they reach the ground and continue their descent as rain. Briefly summarize the collision-coalescence process. The collision-coalescence process occurs in warm clouds, where large cloud drops grow by collecting smaller droplets. Concept Checks 5.5 Compare and contrast rain, drizzle, and mist. The term rain is restricted to drops of water that fall from a cloud and have a diameter of at least 0.5mm. Fine, uniform droplets of water with diameters less than 0.5mm are called drizzle. Precipitation containing the very smallest droplets able to reach the ground is called mist. Describe sleet and freezing rain. Why does freezing rain result on some occasions and sleet on others? Freezing rain and sleet form when falling snow melts in a warm layer, then falls through a subfreezing layer. When the falling rain becomes supercooled and freezes on impact, it produces freezing rain; but if it freezes before reaching the ground, it forms sleet. How does hail form? What factors govern the ultimate size of hailstones? Hail forms high in towering cumulonimbus clouds. Wet growth and dry growth govern the ultimate size of hailstones. Eye On The Atmosphere 5.3 1. What is the name of the process whereby some cloud droplets freeze and grow at the expense of the remaining liquid cloud droplets?

The Bergeron process. 2. Explain why only clouds composed of supercooled droplets can develop “punch holes.” The supercooled water freezes on contact, which leaves a hole where the water once was. 3. Describe the role that a jet aircraft plays in the formation of punch hole clouds. The jet makes contact, causing the supercooled water it touches to freeze, leaving a hole. Concept Checks 5.6 Although any open container can serve as a rain gauge, what advantages does a standard rain gauge provide? A standard rain gauge magnifies rainfall 10 times, allowing for accurate measurement to the nearest 0.025cm. Why is it important to collect both snow depth and water content? The quantity of water in a given volume of snow is not consistent. It may take as much as 30in of light and fluffy dry snow or as little as 4in of wet snow to produce 1in of water. Why is weather radar useful in detecting precipitation? Weather radar tracks both the location and intensity of precipitation. Concept Checks 5.7 What atmospheric condition must exist for cloud seeding to work? Silver iodide crystals. What are some strategies used to reduce fog? Hail? Frost? Fog is reduced by spreading dry ice into layers of supercooled fog or by using helicopters to mix dry air with the saturated, foggy air. Hail is reduced by cloud seeding using silver iodide crystals to disrupt the growth of hailstones. Frost is reduced by conserving heat or adding heat to warm the lowermost layer of air. Describe two inadvertent weather modifications. Two inadvertent weather conditions are the increase in cloud cover caused by contrails from planes, and that major population centers enhance the formation of warm clouds and increase precipitation in these urban areas by as much as 20%....