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Unformatted text preview: Chapter 7: Answers to Questions for Review 1. Microscale: diameter of a few meters or less, time scale of seconds to a few minutes. Example: turbulent eddies. Mesoscale: diameter of a few kilometers to hundreds of kilometers, time scale of hours to a day. Example: thunderstorms. Synoptic scale: diameter of several hundred to a thousand kilometers, time scale of days to weeks. Example: high and low pressure systems. Global scale: spatial scale of entire earth, time scale of weeks to months. Example: longwaves in the westerlies. 2. Wind shear is the change in wind speed or direction with increasing altitude. When the shear exceeds a critical value, waves break into large swirls with significant vertical movement. When this happens in clear air it's called clear air turbulence. 4. During the day, the land heats more quickly than the adjacent water, and the intensive heating of the air above produces a shallow thermal low. The air over the water remains cooler than the air over the land; hence, a shallow thermal high exists above the water. The overall effect of this pressure distribution is a sea breeze that blows from the sea toward the land. At night, the land cools more quickly than the water. The air above the land becomes cooler than the air over the water, producing a distribution of pressure, such as the one shown in Fig. 7.5b.With higher surface pressure now over the land, the wind reverses itself and becomes a land breeze—a breeze that flows from the land toward the water. Temperature contrasts between land and water are generally much smaller at night, hence, land breezes are usually weaker than their daytime counterpart, the sea breeze. 5. During the winter, the air over the continent becomes much colder than the air over the ocean. A large, shallow high-pressure area develops over continental Siberia, producing a clockwise circulation of air that flows out over the Indian Ocean and South China Sea. Subsiding air of the anticyclone and the downslope movement of northeasterly winds from the inland plateau provide eastern and southern Asia with generally fair weather. Hence, the winter monsoon , which lasts from about December through February, means clear skies (dry season), with winds that blow from land to sea. In summer, the wind flow pattern reverses itself as air over the continents becomes much warmer than air above the water. A shallow thermal low develops over the continental interior. The heated air within the low rises, and the surrounding air responds by flowing counterclockwise into the low center. This condition results in moisture-bearing winds sweeping into the continent from the ocean. The humid air converges with a drier westerly flow, causing it to rise; further lifting is provided by hills and mountains. Lifting cools the air to westerly flow, causing it to rise; further lifting is provided by hills and mountains....
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This note was uploaded on 06/23/2008 for the course METR 010 taught by Professor Elajoie during the Spring '08 term at San Jose State.
- Spring '08