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The typical thunderstorms resulting from heating of the atmosphere in the afternoon hours is the best example of ______ rainfall.
The typical thunderstorms resulting from heating of the atmosphere in the afternoon hours is the best example of ______ rainfall.
convective
Thunderstorms are the characteristic form of rain in the ______, wherever cyclonic circulation does not operate.
Thunderstorms are the characteristic form of rain in the ______, wherever cyclonic circulation does not operate.
tropics
Orographic precipitation is caused when air masses are lifted as they move over ______ barriers.
Orographic precipitation is caused when air masses are lifted as they move over ______ barriers.
mountain
Precipitation is generally heavier on the ______ slope than on the leeward slope.
Precipitation is generally heavier on the ______ slope than on the leeward slope.
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A raingage measures the depth and intensity of rain falling on a flat surface without considering infiltration, runoff or ______.
A raingage measures the depth and intensity of rain falling on a flat surface without considering infiltration, runoff or ______.
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The standard raingage known as Symon’s gage has a top opening of ______ cm in diameter.
The standard raingage known as Symon’s gage has a top opening of ______ cm in diameter.
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The recording or automatic raingage weighs the rain which falls into a bucket set on a platform of a spring or level ______.
The recording or automatic raingage weighs the rain which falls into a bucket set on a platform of a spring or level ______.
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For installation, the distance between the raingage and the nearest object should be at least twice the ______ of the object.
For installation, the distance between the raingage and the nearest object should be at least twice the ______ of the object.
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The tipping bucket raingage consists of a 30 cm ______ edge receiver.
The tipping bucket raingage consists of a 30 cm ______ edge receiver.
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When one bucket in a tipping bucket raingage receives 0.25 mm of rainfall, it ______ discharging its contents.
When one bucket in a tipping bucket raingage receives 0.25 mm of rainfall, it ______ discharging its contents.
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The siphon type automatic rainfall recorder is also known as the ______ type of recording raingage.
The siphon type automatic rainfall recorder is also known as the ______ type of recording raingage.
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Errors in rainfall measurements can arise from instrumental defects, improper ______ of the gage, and human errors.
Errors in rainfall measurements can arise from instrumental defects, improper ______ of the gage, and human errors.
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A tendency for droplets to remain small and resist falling is called ______.
A tendency for droplets to remain small and resist falling is called ______.
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The denser the gage network, the more accurate the ______ of rainfall representation.
The denser the gage network, the more accurate the ______ of rainfall representation.
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High variability areas typically have more ______ compared to relatively uniform rainfall areas.
High variability areas typically have more ______ compared to relatively uniform rainfall areas.
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For sufficient rainfall, there must be a good amount of moisture present in the atmosphere to compensate for evaporation losses between ground and ______.
For sufficient rainfall, there must be a good amount of moisture present in the atmosphere to compensate for evaporation losses between ground and ______.
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The adequacy of an existing rain-gage network is assessed ______.
The adequacy of an existing rain-gage network is assessed ______.
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Three major types of precipitation are ______, convective, and orographic.
Three major types of precipitation are ______, convective, and orographic.
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Sampling errors of rainfall tend to increase with increasing mean areal ______.
Sampling errors of rainfall tend to increase with increasing mean areal ______.
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Cyclonic precipitation is caused by lifting associated with horizontal convergence of inflowing atmosphere into an area of ______.
Cyclonic precipitation is caused by lifting associated with horizontal convergence of inflowing atmosphere into an area of ______.
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A warm front occurs when a warm air mass overrides a ______ air mass.
A warm front occurs when a warm air mass overrides a ______ air mass.
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Cold fronts move at a speed of ______ km/h (20-50 mph).
Cold fronts move at a speed of ______ km/h (20-50 mph).
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An occluded front occurs when a cold front overtakes a ______ front.
An occluded front occurs when a cold front overtakes a ______ front.
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The precipitation associated with warm fronts becomes more continuous and ______ as the front approaches an area.
The precipitation associated with warm fronts becomes more continuous and ______ as the front approaches an area.
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The average depth decreases with the area in an ______ function.
The average depth decreases with the area in an ______ function.
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The development of the relationship between maximum depth-area-duration for a region is known as ______ analysis.
The development of the relationship between maximum depth-area-duration for a region is known as ______ analysis.
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Preparation of DAD curves involves considerable ______ effort.
Preparation of DAD curves involves considerable ______ effort.
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The maximum depth for a given storm decreases with the ______.
The maximum depth for a given storm decreases with the ______.
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DAD curves are essential for computing the design ______ in hydrological design.
DAD curves are essential for computing the design ______ in hydrological design.
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Isohyetal maps and mass curves of the storm are ______.
Isohyetal maps and mass curves of the storm are ______.
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Records may be lost due to absence of station ______ or instrumental failure.
Records may be lost due to absence of station ______ or instrumental failure.
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The maximum depth-area curve is prepared by assuming the area distribution of rainfall for smaller ______ to be similar to the total storm.
The maximum depth-area curve is prepared by assuming the area distribution of rainfall for smaller ______ to be similar to the total storm.
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If the normal annual precipitation at each of these stations is within ten percent of that of the station with missing records, a simple arithmetic average of the precipitation at the three stations is used for estimating the missing ______ of the station.
If the normal annual precipitation at each of these stations is within ten percent of that of the station with missing records, a simple arithmetic average of the precipitation at the three stations is used for estimating the missing ______ of the station.
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This method assigns equal weight to all stations irrespective of their relative ______ and other factors.
This method assigns equal weight to all stations irrespective of their relative ______ and other factors.
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The individual weights are multiplied by the station observation and the values are summed to obtain the areal average ______.
The individual weights are multiplied by the station observation and the values are summed to obtain the areal average ______.
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The Thiessen Polygon Method is useful for areas that are more or less plain and are of intermediate size (500 to ______ km2).
The Thiessen Polygon Method is useful for areas that are more or less plain and are of intermediate size (500 to ______ km2).
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The ______ method consists of computing the arithmetic average of the values of the precipitation for all stations within the area.
The ______ method consists of computing the arithmetic average of the values of the precipitation for all stations within the area.
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To apply the Normal Ratio Method, differences in normal annual precipitation must be greater than ______ percent.
To apply the Normal Ratio Method, differences in normal annual precipitation must be greater than ______ percent.
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The stations are plotted on a map of the area drawn to a ______.
The stations are plotted on a map of the area drawn to a ______.
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Rainfall varies in intensity and duration from one place to ______.
Rainfall varies in intensity and duration from one place to ______.
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Study Notes
Conditions for Rainfall Production
- Droplet Growth Mechanism: Requires colloidal stability which helps droplets resist falling by remaining small.
- Droplet Enlargement Processes:
- Speed differences between large and small droplets.
- Coexistence of ice crystals and water droplets.
- Moisture Accumulation: Sufficient atmospheric moisture is necessary to compensate for evaporation losses and facilitate rainfall.
- Types of Precipitation:
- Cyclonic: Caused by horizontal convergence of air.
- Convective: Involves air rising due to heating, leading to variable showers.
- Orographic: Occurs when air is lifted by mountain barriers, resulting in more precipitation on the windward slope.
Cyclonic Precipitation Types
- Non-frontal: Results from air convergence and lifting without front interaction.
- Frontal: Occurs when one air mass is pushed over another, distinguished by temperature and density differences.
- Warm Front: Warm air overrides cold air, leading to widespread cloudiness and continuous rain (speed 15-50 km/h).
- Cold Front: Cold air pushes against warm air, causing intense short-duration precipitation (speed 30-80 km/h).
- Occluded Front: Forms when cold fronts overtake warm fronts, combining features of both types (speed 8-50 km/h).
Rainfall Measurement
- Importance of Rainfall Data: Needed for runoff estimates and irrigation calculations.
- Types of Raingages:
- Non-recording (e.g. Symon’s gage): Measures rain depth without considering evaporation losses.
- Recording: Automated devices to track rain accumulation over time.
Non-Recording Raingage
- Design: A vertical cylindrical container with a wide opening, equipped with a funnel to reduce evaporation.
- Installation Considerations:
- Open area with distance from obstacles to minimize wind effects.
- Level ground preferred for accuracy.
Recording Raingages
- Weighting Bucket Type: Measures rain by weighing the collected water in a bucket that tips when full, recording the data on a mass curve.
- Tipping Bucket Type: Contains two buckets that tip after collecting 0.25 mm of rainfall, triggering an electrical recording mechanism.
- Siphon Type: Uses a float to measure water level, transmitting data to a recording pen on revolving chart; emptied automatically when full.
Errors in Rainfall Measurement
- Instrumental defects, improper siting, and human error are key sources of inaccuracies.
Raingage Network
- Dense networks yield more accurate mean areal rainfall estimates.
- Network setup is influenced by varying rainfall patterns, installation costs, and maintenance.
Depth-Area Relation
- Average depth of rainfall decreases with increasing area, described by an exponential function.
- Maximum Depth-Area-Duration (DAD) Curves: Essential for estimating flood risk, incorporating past rainfall data for analysis.
Interpolation of Rainfall Records
- Approach to estimate missing data using the arithmetic average of nearby stations, especially when records are lost due to various reasons.
- Method choice depends on the similarity of normal annual precipitation among stations.
Methods for Estimating Rainfall Height
- Arithmetic Mean Method: Computes the average across all stations, suitable for uniform distribution.
- Thiessen Polygon Method: Assigns weights to rainfall measurements based on relative areas influenced by each station.
Thiessen Polygon Method Steps
- Map stations on a scale drawing of the area.
- Connect neighboring stations to define polygons affecting rainfall distribution.
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Description
Explore the essential conditions required for rainfall production in this quiz. Understand mechanisms such as droplet growth and moisture accumulation, and how they influence precipitation. Test your knowledge on the intricacies of meteorological processes.
