Chapter 1, Review Questions
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1. Distinguish between weather and climate
a. Weather is the state of the atmosphere at a particular place and time. Variables used to describe weather include: temperature, humidity and cloudiness. Climate describes the weather in an area averaged over a period of time. Weather describes daily atmospheric conditions while climate looks at longer periods of time and utilizes seasonal averages of rainfall, snowfall, and temperature.
2. What is the advantage of describing the climate of locality in terms of both average weather plus extremes in weather?
a. The advantage of describing averages and extremes in weather is particularly useful to farmers. They benefit from not only knowing the average rainfall or temperature for a location but also how often extreme weather occurs in that area.
3. Identify the various sources of weather information that are available to the public.
a. The public may obtain weather reports, maps, and forecasts via NOAA Weather Radio, local television or radio, The Weather Channel or other cable-TV weather reports, newspapers, and the Internet.
4. Describe the type of weather that usually accompanies a high (anticyclone) and a low (cyclone) in middle latitudes
a. Fair weather usually but not always accompanies a high (anticyclone) whereas cloudiness and rain or snow usually but not always accompany a low (cyclone).
5. What is an air mass? What governs the temperature and humidity of an air mass?
a. An air mass is a huge volume of air with uniform temperature and humidity properties that are often indicative of where it was formed. For example, an air mass that develops over a warm ocean surface becomes warm and humid.
6. Explain why clouds and precipitation are often associated with fronts.
a. Fronts are transition zones between two air masses. The property differences and air movements between the air masses give rise to cloudiness and precipitation
7. Among weather satellites, distinguish between GOES and POES.
a. GOES orbits the Earth at a very high altitude but at the same rate as the planet rotates on its axis, so that the satellite is always positioned above the same spot on Earth’s surface (the subsatellite point) and its sensors always observe the same portion of the planet. POES is much closer to the surface but orbits the Earth in a north-south direction passing near the poles. The satellite’s orbit traces out a plane in space while the planet rotates underneath. A sun-synchronous polar-orbiting satellite scans the same area twice a day.
8. What advantages does an infrared satellite image offer over a visible satellite image for monitoring the state of the atmosphere?
a. Infrared satellite sensors detect infrared radiation that is continually emitted to space by the Earth-atmosphere system. Hence, infrared images can be obtained 24 hours a day. Visible satellite sensors detect sunlight reflected by the Earth-atmosphere system. Hence, visible images are possible only during daylight hours.
9. Describe how weather radar detects the location and movement of areas of precipitation.
a. Operating in the reflectivity mode, weather radar locates and tracks the movement of areas of precipitation. Based on the intensity of the reflected signal (echo), weather radar distinguishes the intensity of precipitation. Operating in the velocity (Doppler) mode, weather radar can determine the circulation within thunderstorms and provide early warning of the development of severe weather (e.g., tornadoes).
10. What causes high thin cirrus clouds to appear fibrous or wispy?
a. High thin clouds (e.g., cirrus) are composed of tiny ice crystals that give those clouds a fibrous or wispy appearance.
Chapter 1, Critical Thinking Questions
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1. Identify several of the technological advances of the 20th century that significantly improved weather observation and forecasting.
a. Technological advances of the 20th century included development of new instruments (e.g., radiosonde, radar, satellite sensors) that provide a more complete and accurate representation of the state of the atmosphere (weather), which in turn makes it possible to more accurately initialize numerical models of the Earth-atmosphere system—something that is key to better forecasts. Innovations in communications technologies (e.g., radio, television, Internet) allow rapid transmission of weather information to forecasters and the general public.
2. Why are near-simultaneous weather observations essential for drawing weather maps?
a. The atmosphere is dynamic, that is, the state of the atmosphere varies from one place to another and with time. The most accurate and complete representation of the state of the atmosphere requires weather observations that are taken at the same time and transmitted immediately to weather forecast offices for analysis.
3. How does the local air pressure change as an anticyclone approaches your location?
a. Local air pressure rises as an anticyclone approaches a particular location.
4. Describe the general characteristics of a cloud that may produce lightning, thunder, and heavy rain.
a. A thunderstorm, or cumulonimbus, cloud typically may produce lightning, thunder, and heavy rain. They are puffy cumulus clouds that build vertically, merge laterally, and can reach great altitudes.
5. Explain how it is possible for stratiform clouds at different altitudes to be moving in different directions.
a. Horizontal winds can blow from different directions at different altitudes. Clouds move with the wind so it is possible (in fact, common) for clouds at different altitudes to be observed moving in different directions.
6. Speculate on why the highest temperature of the day usually occurs in mid-afternoon rather than noon.
a. Mid-afternoon is the usual time for the air temperature to reach its maximum because of the culmination of daytime solar heating day up to that point. However, if a cold front passes through a locality in late morning or early afternoon and the new air mass is sufficiently cold, it is possible for the air temperature to drop to its daytime low in mid-afternoon.
7. Describe how the composition and appearance of a cloud change with increasing altitude.
a. The composition and appearance of clouds are impacted by the surrounding air. The air at different levels of the atmosphere can vary greatly, therefore the properties of a cloud vertically building through the atmosphere will vary as well. At lower altitudes, the cloud is typically composed of water droplets, making the cloud edges be sharply defined. At higher altitudes, the cloud is more likely to contain ice crystals and appear more fibrous.
8. Why does snow-covered ground appear bright white on a visible satellite image?
a. A snow-covered area will appear bright white on a visible satellite image because it is a highly reflective surface. Visible satellites produce images of areas that are lit by the sun. A forest or ocean will appear dark while clouds and snow will appear white.
9. In forecasting the weather, what are some of the advantages of overlying a composite radar image on an infrared satellite image?
a. A forecaster will find a radar and infrared satellite composite useful in clearly identifying weather systems. A cold front is more easily recognizable when the both the rain and clouds associated with it can be identified as the most active portion of the system.
10. An intense low pressure system tracks northeastward just offshore from Cape Hatteras, NC to just east of Cape Cod, MA. Describe the general direction of surface winds over New England as the center of the storm moves northward toward Nova Scotia.
a. Winds around a low pressure system blow in a counterclockwise and inward spiral. If the center of a low is near Nova Scotia (which is northeast of New England), then the winds associated with that low will be coming from the west or northwest in New England.