Test 2-PRECIPITATION PROCESSES
What is the basic Bergeron Process?
1. water vapor changing to ice crystals by deposition 2. these ice crystals joining with other ice crystals to make snow crystals & then snowflakes. ****If they melt while falling,then they become a raindrop.****
What is the basic process of the Collision-Coalescence Process?
1. water vapor changing to liquid water droplets (cloud droplets) by condensation 2. these droplets coalescing with other droplets to form raindrops
What is the average conversion of snow to rain?
10 inches of snow is equivalent to 1 inch of rain
What are the two basic mechanisms to explain precipitation formation?
Bergeron Process or Ice-Crystal Process and the Collision-Coalescence Process
example of a rain shadow desert
Great Basin (Nevada deserts) of western U.S.
How is snow formed?
It is formed through the Bergeron Process.
Are sleet and freezing rain counted in precipitation totals?
No
What are the average size and precipitation form of rain droplets?
Rain droplets average between .5 mm to 5 mm in size and are a liquid form of precipitation
What are the common forms of precipitation during the winter time?
Sleet and Freezing rain
What is an example of the West side of STH?
Southeastern U.S.
What season does hail usually occur within?
Summertime
What type of clouds produce hail?
They are only produced in large cumulonimbus clouds, thunderstorms
How is rain created through the Bergeron Process?
Water vapor changes ice crystals in the cloud, then the ice crystals (snowflakes) melts forming a raindrop before it hits the ground.
What are the forms of snow during the Bergeron Process?
Water vapor changes to ice crystals in the cloud (deposition), and the ice crystal(snowflake) remains a snowflake as it hits the ground So, water vapor (gas) to snowflake (solid).
How are raindrops formed through the Collision-Coalescence Process?
Water vapor changes to liquid droplets in the cloud, and these coalesce to form raindrops. These hit the ground as raindrops.
How is rain formed?
Water vapor condenses into liquid water droplets forming clouds. These droplets coalesce (join together) and become heavy enough to be pulled down by gravity as precipitation and do not evaporate before they hit the ground as a raindrop.
What is sleet?
a frozen raindrop. If it starts as a snowflake (Bergeron Process), then it melts to form a raindrop that then freezes (re-freezes) before it hits the ground
What is a monsoon?
an annual cycle of dryness & wetness, with seasonally shifting winds produced by shifting atmospheric pressure patterns.
What is hail?
another form of solid precipitation consisting of hard, rounded pellets or lumps of ice
What occurs within one rain drop?
cloud droplets must coalesce or join together into a raindrop to avoid evaporation
How are Rain shadow deserts formed?
formed by mountain barriers and orographic effects such that the leeward side is often much drier than the windward side.
What is needed for the Bergeron Process?
freezing nuclei to initiate change of water vapor to solid water and thus need Tºs below -10ºC, where both liquid drops & ice crystals can exist. Also need supersaturated conditions (RH > 100%), so ice crystals can collect more water vapor than they lose & thus grow.
What is the process of making freezing rain?
frozen --------------------> liquid ----------------------> liquid/frozen (cloud) (melts in atmo as it falls) (liquid as it hits the ground then re-freezes) OR liquid -----------------------------------------------------> liquid/frozen (cloud) (liquid as it hits the ground then freezes)
What is the characteristics of West side of STH?
greater instability, and wetter conditions.
Air Pressure systems
greatly affect precipitation patterns with areas of Low Pressure typically being unstable (ITCZ) and areas of High Pressure consisting of subsidence and being stable (STH)
What is the maximum size that a raindrop can achieve?
maximum size a raindrop will achieve is about 5 mm
Which clouds do precipitation come from?
precipitation comes from either nimbostratus or cumulonimbus clouds
What is the production of sleet?
rozen ---------------> liquid ------------------------> frozen (cloud) (melts) (in atmo) (re-freezes before it hits ground) OR liquid --------------------------------------------------> frozen (cloud) (freezes in atmo before it hits ground)
What is freezing rain?
similar to sleet except it freezes (re-freezes) after making contact with the ground. This usually involves supercooled raindrops which allows them to freeze on contact with solid objects/surfaces. Commonly referred to as Ice storms.
Examples of area with monsoons
southern Asia (India)
What is the characteristics of East side of STH?
stable, dry conditions
What is the relationship between the velocity and weight of a raindrop?
the larger the raindrop, the faster the raindrop will fall.
What is the Bergeron Process?
the primary process for forming precipitation in the middle and high latitudes and the only process to formation.
What is the Collision-Coalescence Process?
the primary process in tropical areas for raindrop formation in the mid-latitudes during the summer
What are the change of states in the Collision-Coalescence Process?
water vapor (gas) to raindrop (liquid)
What are the forms of water vapor, ice crystals, and raindrops.
water vapor water vapor (gas) to ice crystal(solid) to raindrop (liquid).
What happens within the cloud when there is snow?
within the clouds water vapor changes to ice crystals by deposition
