,ODULE 3

Question 1

is the general term for all forms of moisture emanating from the clouds and falling to the ground.

Answer 1

PRECIPITATION

Question 2

TYPES OF PRECIPITATION

Answer 2

CONVECTIONAL PRECIPITATION
FRONTAL PRECIPITATION
OROGRAPHIC PRECIPITATION
CYCLONIC PRECIPITATION

Question 3

This type of precipitation is in the form of local whirling thunderstorms and is typical of the tropics.
The air close to the warm earth gets heated and rises due to its low density, cools adiabatically to form a cauliflower shaped cloud, which finally bursts into a thunderstorm.
When accompanied by destructive winds, they are called ‘tornados’.

Answer 3

CONVECTIONAL PRECIPITATION

Question 4

When two air masses due to contrasting temperatures and densities clash with each other, condensation and precipitation occur at the surface of contact.

This surface of contact is called a ‘front’ or ‘frontal surface’.

Answer 4

FRONTAL PRECIPITATION

Question 5

If a cold air mass drives out a warm air mass, it is called a ‘cold front’.

Answer 5

COLD FRONT

Question 6

If a warm air mass replaces the retreating cold air mass, it is called a ‘warm front’.

Answer 6

WARM FRONT

Question 7

If two air masses are drawn simultaneously towards a low- pressure area, the front developed
is stationary and is called a
‘stationary front’.

Answer 7

STATIONARY FRONT

Question 8

Cold fronts move faster than warm fronts and usually overtake them, the frontal surfaces of cold and warm air sliding against each other. This phenomenon is called occlusion, and the resulting frontal surface is called an ‘occluded front.

Answer 8

OCCLUDED FRONT

Question 9

This type of precipitation is caused by the uplift of moist air as it flows over a mountain or other elevated terrain.

As the air rises, it cool and condenses, forming clouds
and precipitation.

Answer 9

OROGRAPHIC PRECIPITATION

Question 10

This type of precipitation is due to lifting of moist air converging into a low-pressure belt, due to pressure differences created by the unequal heating of the earth’s surface.

Here the winds blow spirally inward counterclockwise in the northern hemisphere and clockwise in the southern hemisphere.

Answer 10

CYCLONIC PRECIPITATION

Question 11

(also called hurricane or typhoon) of comparatively small diameter of 300-1500 km causing high wind velocity and heavy precipitation,

Answer 11

tropical cyclone

Question 12

large diameter up to 3000 km causing widespread frontal type precipitation.

Answer 12

extra tropical cyclone

Question 13

a light steady rain in fine drops (0.5 mm) and intensity less than 1 mm/h.

Answer 13

Drizzle:

Question 14

the condensed water vapor of the atmosphere falling in drops from the clouds of sizes larger than 0.5 mm. The maximum size is about 6 mm.

Answer 14

Rain

Question 15

freezing of drizzle or rain when they come in contact with cold objects.

Answer 15

Glaze

Question 16

frozen rain drops while falling through air at subfreezing temperature.

Answer 16

Sleet

Question 17

ice crystals resulting from sublimation.

Answer 17

Snow

Question 18

ice crystals fused together.

Answer 18

Snowflakes:

Question 19

small lumps of ice larger than 5 mm in diameter formed by alternate freezing and melting, when they are carried up and down in highly turbulent air currents.

Answer 19

Hail

Question 20

moisture condensed from the atmosphere in small drops upon cool surfaces.

Answer 20

Dew

Question 21

a feathery deposit of ice formed on the ground or on the surface of exposed objects by dew or water vapor that has frozen.

Answer 21

Frost

Question 22

a thin cloud of varying size at the surface of the earth by condensation of atmospheric vapor.

Answer 22

Fog

Question 23

a very thin fog

Answer 23

Mist

Question 24

It refers to the amount of precipitation that falls during a specific time period, typically measured in millimeters or inches per hour. Higher intensity precipitation events are often associated with more extreme weather conditions, such as thunderstorms, hurricanes, or heavy snowfall.

Answer 24

INTENSITY

Question 25

It refers to how often precipitation events of a certain intensity occur over a specific time period, typically measured in terms of the number of events per year. Frequency analysis can be used to identify the probability of extreme precipitation events occurring in a given region, which can help inform planning and management decisions.

Answer 25

FREQUENCY

Question 26

It refers to how long a precipitation event lasts, typically measured in hours. Longer-duration precipitation events can lead to more widespread and sustained impacts, such as flooding or erosion.

Answer 26

DURATION

Question 27

refers to the pattern of where precipitation falls over a specific area. This can be influenced by a variety of factors, such as topography, distance from water sources, and prevailing wind patterns. some regions may experience localized convective precipitation, which is characterized by intense, short-duration storms that are highly variable in space and time.

Answer 27

SPATIAL DISTRIBUTION

Question 28

refers to the pattern of when precipitation occurs over a specific time period, such as a day, a month, or a year. This can be influenced by seasonal and climatic factors, as well as weather patterns such as fronts and atmospheric disturbances.

Answer 28

TEMPORAL DISTRIBUTION

Question 29

It is a rain gauge which does not provide the distribution of amount of precipitation in a day. It simply gives the amount of precipitation after 24 hours (daily precipitation).

Answer 29

NON-RECORDING RAIN GAUGES

Question 30

This is also called self-recording, automatic or integrating rain gauge. This type of rain gauge has an automatic mechanical arrangement consisting of a clockwork, a drum with a graph paper fixed around it and a pencil point, which draws the mass curve of rainfall. From this mass curve, the depth of rainfall in a given time, the rate or intensity of rainfall at any instant during a storm, time of onset and cessation of rainfall, can be determined.

Answer 30

RECORDING RAIN GAUGES

Question 31

This consists of a cylindrical receiver 30 cm diameter with a funnel inside. Just below the funnel a pair of tipping buckets is pivoted such that when one of the bucket receives a rainfall of 0.25 mm it tips and empties into a tank below, while the other bucket takes its position, and the process is repeated. The tipping of the bucket actuates on electric circuit which causes a pen to move on a chart wrapped round a drum which revolves by a clock mechanism. This type cannot record snow.

Answer 31

TIPPING BUCKET RAIN GAUGE

Question 32

In this type of rain-gauge, when a certain weight of rainfall is collected in a tank, which rests on a spring- lever balance, it makes a pen to move on a chart wrapped round a clock-driven drum. The rotation of the drum sets the time scale while the vertical motion of the pen records the cumulative precipitation.

Answer 32

WEIGHING TYPE RAIN GAUGE

Question 33

as the rain is collected

Answer 33

float chamber

Question 34

the float moves up which makes a pen to move on a chart wrapped round a clock driven drum. When the float chamber fills up, the water siphons out automatically through a siphon tube kept in an interconnected siphon chamber. The clockwork revolves the drum once in 24 hours. The clock mechanism needs rewinding once in a week when the chart wrapped round the drum is also replaced.

Answer 34

FLOAT TYPE RAIN GAUGE

Question 35

Point rainfall is the rainfall at a single station. For small areas less than 50 square kilometers, point rainfall may be taken as the average depth over the area. In large areas, there will be a network of rain gauge stations. As the rainfall over a large area is no uniform,

Answer 35

MEAN AREAL DEPTH

Question 36

It is obtained by simply averaging arithmetically the amounts of rainfall at the individual rain-gauge station in the area Pave = P1 + P2 + P3 + ⋯ + Pn/ n = σi=1Pi/n This method is fast and simple and yields good estimates in flat country if the gauges are uniformly distributed and the rainfall at different stations do not vary very widely from the mean.

Answer 36

ARITHMETIC AVERAGE METHOD

Question 37

This method attempts to allow for non uniform distribution of gauges by providing a weighting factor for each gauge. The results obtained are usually more accurate than those obtained by simple arithmetic averaging. The gauges should be properly located over the catchment to get regular shaped polygons.

Answer 37

THIESSEN POLYGON METHOD

Question 38

In this method, the point rainfalls are plotted on a suitable base map and the lines of equal rainfall (isohyets) are drawn giving consideration to orographic effects and storm morphology.

Answer 38

ISOHYETAL METHOD

Question 39

used to summarize precipitation data, such as the mean, median, and standard deviation of precipitation amounts.

Answer 39

Descriptive Statistics

Question 40

involves analyzing the changes in precipitation amounts over time, such as seasonal or annual trends.

Answer 40

Time-Series Analysis

Question 41

involves analyzing the distribution of precipitation across a region or area, such as the variation in precipitation amounts between different cities or regions.

Answer 41

Spatial Analysis