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26 Cards in this Set
- Front
- Back
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How can collision-coalescence occur?
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requires existence of large droplets and different fall speeds
different sizes allow for different velocities which cause collisions |
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What two physical processes combine to determine the depositional growth rate
(dR/dt, dm/dt)? |
combine mass diffusion and heat conduction (with heat balance)
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How does the freezing temperature differ in homogeneous and heterogeneous
nucleation for ice? |
hetero: -20
homo: -40 so homo freezing temp is much lower than hetero |
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What is radar? Why WSR-88D radar network is being upgraded with dulapolarization
capability? |
RAdio Detection And Ranging of objects
A remote sensing system consisting of an antenna, transmitter, receiver, signal processor and display. Dual-polarization radar provides more information about cloud/precipitation microphysics. |
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What are the main advantage of weather radars over optical sensors?
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3-D spatial distribution and time evolution (4-D weather information), especially information
inside storms |
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Why do ice crystals grow faster than cloud droplets even though they both grow by diffusion below freezing?
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Vapor saturation pressure over ice is lower than that over water; hence, the
supersaturation ratio is larger for ice crystals than for cloud droplets. |
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What is the difference in density of hailstones formed through wet growth and those formed through dry growth?
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Density of hailstones from wet growth is higher than that from dry growth
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How does the collision process generate electric charge?
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Collectees lose electrons to collectors to have a net positive charge while
collectors become negatively charged. Hence, separated charges are generated. |
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What is lightning? What are the three stages?
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Lightning is a process of electrostatic discharge. The three stages are:
preliminary breakdown, leader and return strike |
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What is a rainbow? What are the primary and secondary rainbows, respectively?
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A rainbow is an optical and meteorological phenomenon that causes a spectrum of light to appear in sky.
Primary rainbow forms about 41 degree from the antisolar point, which involves a single reflection inside the water droplets. The secondary rainbow involves double reflections inside the droplets. |
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which nucleation process is easier? homogeneous or heterogeneous?
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heteorogeneous since there is a foreign substance (aerosol) present
hetero requires a lower saturation than homo.. homo needs a few 100% |
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opposite of condensation
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evaporation
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opposite of deposition
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sublimation
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collision and coalescence condition and meaning
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condition: warm rains, diff drop sizes with diff velocities
meaning: capture of small cloud droplets by large cloud or rain droplets |
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aggregation condition and meaning
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condition: ice phase necessary for fast growth, diff drop sizes
meaning: clumping together of ice crystals to form snowflakes |
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nucleation condition and meaning
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condition: 1. need supersaturation 2. particle r>r*
meaning: process of cloud droplet formation overcoming energy barrier |
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condensation condition and meaning
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condition: e> es
meaning: process of going from water vapor to a liquid |
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evaporation condition and meaning
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condition:
meaning: process of going from liquid to water vapor |
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deposition condition and meaning
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condition: e>ei
meaning: process of going from water vapor directly to ice |
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sublimation condition and meaning
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condition:
meaning: process of going from ice to water vapor |
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convective rain
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localized and showery precip associated with cumulus-scale convection of unstable air
high humidity and large cloud water contents coalescence = important process accretion growth cloud properties vary with time but are constant with height at any time fast process short time available for precip growth |
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stratiform rain
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widespread and continuous associated with large scale ascent produced by frontal or topographic lifting or large scale horizontal convergence unstable air
developed by ice phase process low liquid water contents lower number concentration slow process each level has diff precip process |
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accretion condition and meaning
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condition: phase change between ice and liquid or visa versa
meaning: capture of supercooled droplets by a ice-phase precip particle |
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what shape are raindrops and why?
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oblate spheroid
because of aerodynamic drag |
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melting
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condition: phase change, temps above 0 degrees C
meaning: going from ice to liquid |
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freezing
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condition: phase change, temps below 0 degrees C
meaning: going from liquid to ice |
