Precipitation Flashcards
The process by which water vapor in the air is changed into liquid water.
Condensation
The process by which water vaor in the air is changed into solid without becoming liquid.
Sublimation/Deposition
All forms of water that forms in the atmosphere and falls back to the earth’s surface.
Precipitation
The condensation into water droplest and sublimation into ice crytals of atmosphere water vapor generally occur around?
Condensation/Sublimation Nuclei
Principal types of nuclei?
Dusts, Ocean Salt, Products of combustion and oxides of nitrogen, Other particulate of matter (less than a micron in diameter)
The primary cause of condensation and hence, is responsible for most precipitation.
Adiabatic Cooling
Adiabatic Cooling results mainly from (blank) which results from a (blank)?
Expansion of air mass, Decrease in atmospheric pressure
Adiabatic cooling is triggered primary by the?
upward or vertical motion of air mass
The other cause of condensation or sublimation aside from adabatic cooling?
Mixing of air mass of varying temperatures, radiation cooling and contact cooling.
The (blank) process is when the cloud droplets collide and coalesce or stick together.
Collision - Coalescence
Forms of precipitation?
Rain, Snow, Drizzle, Glaze, Sleet, Hail, Graupel
Form of water drops of sizes larger than 0.5 mm
Rain
Light rain
2.4 mm/hr
Moderate Rain
2.5 - 7.5 mm/hr
Heavy Rain
> 7.5 mm/hr
Consists of ice crystal which usually combine to form flakes.
Snow
A fine sprinkle of numerous water droplets of size less than 0.5 mm and intensity less than 1 mm/hr.
Drizzle
When rain drizzle comes in contact with cold ground at around 0degC, the water drops freeze to form an ice coating.
Glaze
It is frozen raindrops of transparent grains which form when rain falls through air at subfreezing temperature.
Sleet
it is a showery precipitation in the form of irregular pellets or lumps of ice of size more than 8 mm.
Hail
Also called snow pellets or soft hail, as the (blank) particles are particularly fragile and generally disintegrate when handled.
Graupel
Types of Precipitation
Convection Precipitation, Orographic Precipitation, Cyclonic Precipitation
Results from the differential heating of air masses near the ground surface resulting in the upward movement of warmer air masses.
Convection Precipitation
Precipitation influenced by topography.
Orographic Precipitation
Associated with the movement of air masses due to differences in barometric pressure.
Cyclonic Precipitation
The mean annual rainfall of the Philippines varies from?
965 - 4,064 mm
Receives the greatest amount of rainfall in the Ph?
Baguio City, Eastern Samar, Easrtern Surigao
Receives the least amount of rainfall in the Ph?
Southern part of Cotabato
What is the average annual rainfall in General Santos City in Cotabato?
978 mm
The precipitation is collected and measured in a?
Rain Gauge
(Blank) are sometimes referred to as rain gauge.
Pluviometer, Ombrometer, Hyetometer
Classifications of rain gauges?
Non - recording gauges, and Recording Gauges
Non - Recording Gauges
Symon’s Gauge, Standard 8-inch Rain Gauge
Recording Gauges
Tipping-Bucket Type, Weighing-Busket Type, Natural-Siphon Type, Telemetering Rain Gauges, Radar Measurement of Rainfall
The catch from the funnel falls onto one of a pair of small buckets.
Tipping-Bucket Type
The catch from the funnel empties into a bucket mounted on a weighing scale. The weight of the bucket and its contents are recorded on a clockwork - driven chart.
Weighing-Busket Type
Also known as float-type gauge. The rainfall is collected by a funnel-shaped collector led into a float chamber using a float to rise.
Natural-Siphon Type
Recording type and contain an electronic units to transmit the data on rainfall to a base station both at regular intervals and on interrogation.
Telemetering Rain Gauges
Ground-based radars send out pulses of microwave energy in narrow beams that scan in a circular pattern.
Radar Measurement of Rainfall
In flat region of temeperate, Mediterranean and tropical zones
Ideal - 1 station for 600 - 900 sq.km, Acceptable - 1 station for 900 - 3000 sq.km
In mountainous regions of temeperate, Mediterranean and tropical zones
Ideal - 1 station for 100 - 250 sq.km, Acceptable - 1 station for 25 - 1000 sq.km
In arid and polar zones
1 station for 1500 - 10,000 sq.km depending on feasibility
(Blank) of rain gauge stations should be equipped with self - recording gauges to know the rainfall intensities.
0.1
Based on the principle that when recorded data comes from the same parent population, they are consistent.
Double - Mass Curve
Test for consistency of record.
Double - Mass Curve
Presentation of Rainfall Data
Mass Curve of Rainfall, Hyetograph, Point Rainfall, Moving Average,
Plot of the accumulated precipitation against time, plotted in chronologica; order.
Mass Curve of Rainfall
Plot of the intensity of rainfall against the time interval. It is derived from the mass curve and is usually represented in bar chart/graph.
Hyetograph
Also known as station rainfall, refers to the rainfall data of a station. Graphically, these data are represented as plots of magnitude vs. chronological time in the form of bar diagram.
Point Rainfall
A technique for smoothening out the high frequency fluctuations of a time series and to enable the trend, if any, to be noticed.
Moving Average
Mean Precipitation Over an Area
Arithmetic Mean Method, Thiessen Polygon, Isohyetal Method
This method is use when rainfall over a catchment show little to no variation.
Arithmetic Mean Method
This method is use when the rainfall recorded at each station is given a weightage on the basis of an area closest to the station.
Thiessen Polygon
This method is use when the area of two adjacent isohyets are determined and the average value of rainfall indicated by the two isohyets is assumed to be acting over the inter - isohyet area.
Isohyetal Method
