a science that studies the atmosphere and the

movement of water either vapor or liquid in the atmosphere

Vertical and horizontal

movement of water as either vapor, liquid, or solid between the earth’s surface, subsurface,

atmosphere, and oceans that occurs continuously in nature.

process whereby liquid water is converted to water vapour

(vaporization) and removed from the evaporating surface such as adjacent soil,

water surfaces such as lakes, ponds, etc.

The process of liquid water vaporization/removal contained in plant

tissues to the atmosphere through the stomata

Process by which water vapor becomes a liquid.

condensation forms clouds which then resulted to precipitation. It is

the fall of moisture from atmosphere to the earth’s surface in any form

it is the water flowing over the land making its way towards rivers, lakes,

oceans etc. as surface or subsurface flow

process of filtration of water to the inner layers of soil based on its

structure and nature

vertical movement of water through the soil profile

precipitations that are evaporated

immediately without reaching the ground

ratio of runoff to rainfall

An

area that topographically appears to contribute all the water that passes through a specified

cross section of a stream (the outlet).

An area of land that drains water, sediment and dissolved materials to a common receiving

body or outlet.

Boundary line along topographic ridges that

separates two adjacent watersheds; defined by the highest elevation that

drains a stream.

stream that flows into a larger stream or other

body of water

are smallest streams at the outer

limits of a watershed

form when first order streams meet

located in a single point at which all surface drainage from a basin comes together or concentrates as outflow from the basin in the stream channel

process of identifying and delineating the boundary or divide of a

watershed

refers to the rate of change of elevation to the distance

along the principal flow path

occurs when precipitation have satisfied the demands of evaporation,

interception, infiltration, surface storage, surface detention and channel detention

the quantity of surface water that flows in a stream or river over a fixed period

of time

refers to the height of water surface or stream level measured from an arbitrary datum (it can be the mean sea level)

graduated staff made of durable materials that are fixed rigidly to structure

installed vertically into the cross section of a stream

are gauges that measures the water level from above the surface such as bridges or other structure

These are automatic stage recorder, float movement fluctuates with

change in stage and this is recorded by a chart.

Measures the velocity of water by correlating the revolution of the propeller produced by the water current, it is more applicable to larger streams or rivers.

a chronological graphical representation of the stage or discharge of a river or a lake

also called excess rainfall, is the amount of rainfall that becomes the direct runoff at the watershed outlet

it is the time from the beginning of the rising limb to the occurrence of the peak discharge

it is the time required for water to travel from the most hydraulically remote point in the basin to the basin outlet

it is the time between the center of mass of the effective rainfall hyetograph and the center of mass of the direct runoff hydrograph

it is the duration of the direct runoff hydrograph

graph of rainfall after initial losses and infiltration losses are removed, also a graph for effective rainfall

A rechargeable resource widely distributed under the ground which can be used to supplement water supply in irrigation and other usage.

A water bearing geologic formation or stratum capable of transmitting water through its pores at a rate sufficient for economic extraction by wells.

A geologic formation, which can absorb water but cannot transmit significant amounts.

A geologic formation of rather impervious nature, which transmits water at a slow rate compared to an aquifer (insufficient for pumping from wells).

A geologic formation with no interconnected pores and hence can neither absorb nor transmit water. These are formations made of massive compact rocks without any fractures.

an aquifer just beneath the water table; a groundwater that is not confined by a strata under pressure higher than atmospheric

wells that are drilled into unconfined aquifer

occurs whenever a groundwater body is separated from the main groundwater by a relatively impermeable stratum of small areal extent and by the zone of aeration above the main body of groundwater

occurs when groundwater is confined under pressure greater than atmospheric pressure by an overlying impermeable stratum

In confined aquifer it is an imaginary line that coincides with the hydrostatic pressure level of the water in the aquifer. Also defines the water level in a well drilled into a confined aquifer.

water held tightly to the surface of the soil particle by adsorption forces

water held by forces of surface tension and continuous film around soil particles

known as “groundwater”, also known as “phreatic zone” where all layers are filled with water under hydrostatic pressure;

volume of water expressed as a percentage of the total volume of the saturated aquifer that will drain by gravity when the water table drops due to pumping or drainage

It states that “the velocity of flow in a porous medium is proportional to the

hydraulic gradient”.

slope of the water level/piezometric level or simply the change in water level/piezometric level per unit distance along the direction of maximum head decrease

flow capacity of an aquifer per unit width under unit hydraulic gradient and is equal to the product of permeability times the saturated thickness of the aquifer

reduction of hydraulic head or the distance at which the water level is lowered

The discharge per unit drawdown in the well. It is a measure of the effectiveness of the well.

the overall instantaneous condition of the atmosphere at a certain place and time

refers to the state of the atmosphere for a given place over time; average of many

years of weather observation (30 years)

relatively thin, gaseous envelope that comprises mostly nitrogen and oxygen,

with small amounts of other gases, such as water vapor and carbon dioxide (CO2)

Any form of water particles—liquid or solid—that falls from the atmosphere and

reaches the ground.

a light steady rain in fine drops that are < 0.5 mm in size and intensity of <1 mm/hr.

the condensed water vapour of the atmosphere falling in drops that are >0.5 mm in size (maximum size—6 mm) from the clouds

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

Form of precipitation where frozen rain drops while falling through air at subfreezing temperature

Form of precipitation where ice crystals resulting from sublimation (i.e., water vapour condenses to ice).

Form of precipitation where ice crystals fused together.

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

Form of precipitation where moisture condensed from the atmosphere in small drops upon cool surfaces

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

A thin cloud of varying size formed at the surface of the earth by condensation of atmospheric vapour (interfering with visibility).

a very thin fog

This type of precipitation is in the form of local thunderstorm. Air on the earth’s surface is heated causing them to rise forming thunderstorms.

occurs when cold air mass advances towards a warm air mass

occurs when warm air mass move towards cold air mass

occurs when cold front overtakes a warm front

occurs when neither cold and warm air masses advances

Precipitation type caused by a barrier, e.g., mountain range.

Precipitation type caused by air converging into a low-pressure area, e.g., cyclones.

process of producing precipitation by liquid particles through colliding and joining

Precipitation process that involves tiny ice crystals in a supercooled cloud growing larger at the expense of the surrounding liquid droplets.

any instrument designed to measure rain amount

a recording rain gauge in which the water collected continuously drains through a funnel into one of a pair of chambers or buckets that are balanced stably on a horizontal axis

a recording rain gauge in which the weight of water collected is measured as a function of time and converted to rainfall depth

A probe consisting of a stainless-steel rod covered by a Teflon sheath set inside a cylindrical rainwater collector.

a gauge that measures the scintillation in an optical beam produced by raindrops falling between a light source and an optical receiver

a rain gauge capable of measuring very small amounts of precipitation, amounts that are less than could be measured by an ordinary rain gauge

Thermometer measures the average speed/motion of molecules, faster motion corresponds

to _____.

A thermometer that utilizes the thermal properties of gas.

A thermometer in which the thermally sensitive element is a liquid contained in a graduated glass envelope.

A thermometer using transducing elements that deform with temperature.

A thermometer that uses a transducing element with electrical properties that are a function of its thermal state.

A thermometer based on the principle that the velocity of a sound wave is a function of the virtual temperature of the medium through which it passes.

A thermometer in which the thermally sensitive element is a liquid contained in a metal envelope, frequently in the form of a Bourdon tube.

the temperature at which saturation occurs

The lowest temperature that can be obtained by evaporating water into the air

The temperature of air measured by a thermometer that is freely exposed to the air but shielded from radiation, also commonly referred to as the air temperature.

The difference in degrees between the air temperature (dry-bulb temperature) and the wet-bulb temperature.

special type of aneroid barometer that converts pressure to altitude

Standard atmospheric pressure

tells us the mass of water vapor in a fixed volume of air, or the water vapor density

the mass of the water vapor in the air parcel over the mass of all the air in the parcel (including vapor)

the mass of the water vapor in the parcel over the mass of the remaining dry air

is the ratio of the amount of water vapor actually in the air to the maximum amount of water vapor required for saturation at that particular temperature (and pressure)

Any instrument that measures the water vapor content of the atmosphere.

an instrument use to measure wind speed and direction

a seasonal change in wind direction caused by a change in the dominant atmospheric pressure pattern

visible aggregate of tiny water droplets or ice crystals suspended in the air

Are “water-seeking,” and water vapor rapidly condenses on their surfaces.

it is the total electromagnetic radiation emitted by the sun

solar radiation that has not been scattered or absorbed

Solar radiation, direct and diffuse, received from a solid angle of 2π steradians on a horizontal surface.

Solar radiation that is scattered at least once before it reaches the surface.

measures the intensity of direct solar radiation

measures global radiation (the combined intensity of direct solar radiation and diffuse sky radiation)

measures the effective terrestrial radiation

a type of actinometer, an instrument that measures the intensity of radiant energy by employing a thermally sensitive electrical resistor

an instrument for measuring the ultraviolet in solar and sky radiation

An instrument for measuring the luminance, luminous intensity, or illuminance of a light source.

An instrument that measures radiated electromagnetic power.

Also called as “consumptive use”, total water lost from a cropped (or irrigated) land due to evaporation from the soil and transpiration by the plants.

loss of water from adjacent soil, water surfaces and leaf surfaces

water loss from water entering the plant roots and out to the atmosphere

is represented by the evapotranspiration from a standardized vegetated surface or reference surface.

The following are assumptions of reference crop evapotranspiration, except:

Way to compile data for frequency analysis where series of extreme events each year (e.g., daily maximum rainfall).

Way to compile data for frequency analysis where all values above a given base are chosen regardless of the number within a given period.

Period within which an event (e.g., rainfall intensity, runoff amount) for a given duration will be equaled or exceeded once on the average; average number of years necessary for the event to occur once, in any given year.

flow of water under gravitational force through permeable layers; lateral movement of water in the soil