Precipitation Flashcards
What happens to the humidity of air as water droplets grow?
It decreases
Why do most clouds not produce rain?
Because the process of condensation of water into droplets is too slow to build
How do raindrops form in a cloud?
By collision and coalescence
What do drops fall at?
Their terminal velocity
What’s the most important factor in producing raindrops?
A clouds moisture content
What do ice crystals need to grow on?
Ice nuclei
What do ice crystal shapes depend on?
Growth temperature
How is sleet formed?
By rain falling through a deep freezing layer of air
What is freezing air caused by?
Rain falling through a thin layer of cold air that supercools the rain below 0 degrees. This supercooled rain freezes on contact
How is hail formed?
By frozen raindrops being swept in violent updrifts within cumulonimbus clouds.
Methods of measuring precipitation?
-Simple raingauge is a funnel that feeds into a measuring cylinder
-Common electronic gauges consist of a funnel that feeds either:
1. An electronic drop counter
2. A pair of tipping buckets on a rocker
How does a rain radar work?
Radar pulses of 30-100mm wavelength are scattered back by falling rain. By timing the returning pulses, the distance away of the rain can be measured and displayed.
