2.0 Precipitation Flashcards
general term for all form of moisture originating from clouds and falling to the ground.
precipitation
consists of waterdrops under 0.02 in diameter and intensity is usually less than 0.04 in/br
drizzle
consists of drop usually greater than 0.02 in diameter. 0.25 in upper limit of raindrop size.
rain
is the ice coating formed when drizzle or rain freezes as it comes in contact with cold objects at the ground.
glaze
frozen raindrops that fall as small globose, ice pellets with a diameter of 5mm or less
sleet
precipitation in the form of ice crystals resulting from sublimation
snow
made up of a number of ice crystals fused together
snowflake
precipitation in the form of balls or lumps of ice over 0.2 in diameter.
hail
types of precipitation
convective precipitation
cyclonic precipitation
orographic precipitation
factors determining precipitation
climate
geography
ocean surface
forms of precipitation
liquid
solid
types of liquid precipitation
rainfall
drizzle
types of solid precipitation
snow
hail
sleet
caused by natural rising of warmer lighter air at colder denser surrounding
covective precipitation
results from lifting of air converging into a low-pressure area or cyclone
cyclonic precipitation
occurs when heavily moisture laden air stops due to topographic conditions (mountains)
orographic precipitation
weather system for precipitation
atmospheric front
cyclone
anticyclones
interface b/w two distinct air masses
front (atmospheric front)
large low pressure region with circular wind motion
cyclone
regions of high pressure, usually of large areal extent
anticyclones
amount of precipitation, in the form of rain (water from clouds), that descends onto the surface of Earth, whether it is on land or water.
Rainfall
falling snowflakes or snow crystals or also the accumulation of snow during a specified period of time.
Snowfall
The formation of snow requires at least 3 conditions
1) atmospheric moisture and
2) mechanisms to convert this water vapor into precipitation (i.e. vertical motion of air),
3) temperatures (T) below 0oC.
instruments in measuring snowfall
- 4” Diameter CoCoRaHS Rain Gauge(Outer Cylinder for winter weather)
- Snow Measuring Board(16”x16” piece of ½ or ¾ plywood painted white)
- Snow ruler or Yardstick(Measure in 10th`s of an inch)
- CoCoRaHS “Snow-Swatter” and Spatula(Helps with taking core samples)
simplest averaging method but can only be relied on small, flat areas
Arithmetic mean method
a graphical technique that considers the weights of each rain gages based on the relative measurements of their respective area coverage. done by connecting the rain gages with a line and drawing a perpendicular bisector
Thiessen polygon method
graphical technique that involves drawing isohyets or contours that are equal to the respective rainfall gage over an area based on point measurements. most technical method as it also takes the topography of the area into consideration, but doing so makes it the most accurate method among the three basic averaging methods
Isohyetal method
methods in estimating rainfall average
arithmetic mean method
thiessen polygon method
isohyetal method
methods in estimation of missing data
arithmetic mean method
normal ratio method
defined as a change in the amount of precipitation that falls naturally in a certain location
Variation of precipitation
occur seasonally or within a single storm, and distributions vary with storm type, intensity, duration, and time of year
Time variations of precipitation
In general, precipitation is heaviest at the equator and decreases with increasing latitude.
True