Hydrology Notes.docx

Hydrology – treats of the waters of the Earth, their occurrence, circulation, and distribution, their chemical and physical properties and their reaction with their environment, including their relation to living things. Hydrologic Cycle – the sequence of conditions through which water passes from vapor in the atmosphere through precipitation upon land or water surfaces and ultimately back into the atmosphere as a result of evaporation and transpiration. Actinometer and Radiometer – used to measure intensity of radiant energy.

Anticyclone – area of relatively high pressure in which the winds tend to blow spirally outward in clockwise direction in the northern hemisphere. Frontal Surface – is the boundary between two adjacent air masses of different temperature and moisture content. Surface Front – The line of intersection of a frontal surface with the Earth. Upper-Air Front – is formed by the intersection of two frontal surfaces aloft. Warm Front – Warm air displaces colder air. Cold Front – Cold air displaces warmer air.

Pyrheliometer – measuring of intensity of direct solar radiation.

Stationary Front – Front is not moving.

Pyranometer – Measuring shortwave radiation.

Occlusion – Cold fronts move faster then warm fronts and usually overtake them.

hemispherical

Pyrgeometer – Measuring of hemispherical longwave radiation. Pyrradiometer or Total Hemispherical Radiometer – Measuring of all wave radiation flux.

Occluded Front – Resulting Surface front. Lapse Rate – is the rate of change of temperature with height in the free atmosphere. Sublimation – The direct transformation from ice to vapor and vice versa.

Jet Streams – Caused by air masses being brought into motion by strong pressure gradient forces.

Condensation – The process by which water vapor changes to liquid or solid state.

Tropopause – The boundary troposphere and stratosphere.

Latent heat of Vaporization – amount of heat absorbed by a unit mass of a substance without change in temperature while passing from liquid to the vapor state.

between

Troposphere – Which extends from the Earth’s surface to the tropopause. Stratosphere – Is the relatively isothermal layer extending from the tropopause to about 20 to 25 km. Cyclone – is more or less a circular area of low atmospheric pressure in which the winds blow counterclockwise in the northern hemisphere. Tropical Cyclone – form at low altitudes and may develop into hurricanes or typhoons.

Latent Heat of Sublimation – For water is the amount of heat required to convert one gram of ice into vapor. Hair Hygrometer – makes use of the fact that the length of a hair varies with relative humidity. Hair Hygrograph – is a hair hygrometer operating a pen marking a trace on a chart. Hygrothermograph – combining features of both hair hygrograph and thermograph.

Dewpoint hygrometer – which measures dewpoint directly and is used mostly for laboratory purposes.

Cold Front Precipitation – formed in the warm air forced upward by an enhancing mass of cold air.

Dew-Cell Hygrometer – measure the dewpoint by regulating the temperature of a saturated aqueous lithium chloride solution.

Orographic Precipitation – mechanical lifting over mountain barriers

Spectral Hygrometer – Measure the selective absorption of light in certain bands of the spectrum by water vapor. Wind – air in motion, very influential factor in several hydrometeorological processes. Anemometers – measures wind speed. Moisture – is always present in the atmosphere. Hydrometeor – any product of condensation of atmospheric water vapor. Drizzle – sometimes called mist, consists of tiny water droplets usually with diameters of 0.1 and 0.5 mm. Rain – consists of liquid water drops. Glaze – is the ice coating. Rime – is a white opaque deposit of ice granules. Snow – is composed of ice crystals. Hail – is precipitation in the form of balls of ice. Sleet – consists of transparent, globular, solid grains of ice. Cyclonic Precipitation – result from the lifting air converging into a low-pressure are or cyclone. Frontal Precipitation – results when the leading edge of a warm, moist air mass (warm front) meets a cool and dry air mass (cold front). Warm front precipitation – is formed in the warm air advancing upward over a colder air mass.

Weather Control or Weather Modification – general effort to alter artificially the natural meteorological phenomena of the atmosphere. Cloud modification or cloud seeding – a type of weather modification, its goal either dissipation of the cloud or stimulation of precipitation. Tipping-bucket gage – the water caught in the collector is funneled into a two-compartment bucket. As the bucket is tipped it actuated an electrical circuit. Weighing-type Gage – weighs rain or snow which falls into a bucket set on the platform of a spring or lever balance. Float Recording Gages – the rise of float with increasing catch of rainfall is recorded. Double-mass analysis – tests the consistency of the record at a station by comparing its accumulated annual or seasonal precipitation. Thiessen Method – attempts to allow for nonuniform distribution of pages by providing a weightlifting factor for each gage. Grid Point Method – Averages the estimated precipitation at all points pf a superimposed grid. Isohyetal Method – most accurate method. Station locations and amounts are plotted on a suitable map, and contours of equal precipitation are then drawn. Aerial Snow- Depth markers – a type of stake adapted for visual reading from low lying aircraft, are used in some remote areas. Snow density – the ration between the volume of meltwater from a sample of snow and initial volume pf the sample.