Chat with AIExam 7: Precipitation
Why are large snowflakes usually observed when the air temperature near the ground is just below freezing?
(72) 
VerifiedSnowflakes that fall through moist air that is slightly above freezing slowly melt as they descend. A thin film of water forms on the edge of the flakes, which acts like glue when other snowflakes come in contact with it. In this way, several flakes join to produce giant snowflakes often measuring several inches or more in diameter. These large, soggy snowflakes are associated with moist air and temperatures near freezing. However, when snowflakes fall through extremely cold air with a low moisture content, small, powdery flakes of "dry" snow accumulate on the ground.
Condensation onto hygroscopic nuclei is possible at relative humidity less than 100 percent due to the ____.
(72) VerifiedC
How does the ice-crystal (Bergeron)process produce precipitation? What is the main premise describing this process?
(81) VerifiedThe main premise is that the saturation vapor pressure just above a water surface is greater than the saturation vapor pressure above an ice surface. This difference in vapor pressure causes water vapor molecules to move (diffuse)from the droplet toward the ice crystal. The removal of vapor molecules reduces the vapor pressure above the droplet. Since the droplet is now out of equilibrium with its surroundings, it evaporates to replenish the diminished supply of water vapor above it. This process provides a continuous source of moisture for the ice crystal, which absorbs the water vapor and grows rapidly. Hence, during the ice-crystal (Bergeron)process, ice crystals grow larger at the expense of the surrounding water droplets.
The primary method used in preventing the growth of large, destructive hailstones is to inject a thunderstorm with large quantities of ____.
(67) A raindrop is falling at constant speed. This constant speed is also called ____________________.
(71) In a standard rain gauge ____ inches of water in the tube would be measured as 1 inch of rainfall.
(73) Small raindrops fall ____ large raindrops, and have ____ terminal velocity than/as large raindrops.
(75) Radar gathers information about precipitation in clouds by measuring the ____.
(81) Radio detection and imaging is the spelled-out version of the acronym ____________________.
(82) The idea in cloud seeding is to first find clouds that have too low a ratio of ice crystals to droplets and then to add enough artificial ice nuclei so that the ratio of crystals to droplets is about ____.
(80) When a Doppler radar has collected data, the returning signal is amplified and displayed on a screen, producing an image, also called a(n)____________________, from the target.
(71) Large, heavy snowflakes are associated with moist air and temperatures well below freezing.
(67) Given that precipitation can be accurately measured at surface weather stations, explain why it is desirable to measure rainfall from space.
(77) The next improvement for Doppler radar is called the ____________________. This form of Doppler radar, which has been installed around the United States over the last several years, transmits both a vertical and horizontal pulse, which makes it easier to determine whether falling precipitation is in the form of rain or snow.
(87) Satellites measure rainfall from space using which instrument?
(90) When the temperature in a cloud is -30 degrees Celsius, smaller cloud droplets are more likely to freeze than larger cloud droplets.
(73) 
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