DEFINITION OF TERMS
Following are
definitions of some common terms used in various issuances such as forecasts
and advisories.
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Weather
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the specific
conditions of the atmosphere at a particular place and time. It is measured
in terms of such parameters as wind, temperature, humidity, atmospheric
pressure, cloudiness and precipitation. In most places, weather can change
from hour to hour and season to season.
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Climate
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the average
weather and its long term variability over a particular place and time (say a
month, a season, a year or several years).
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Climate
Variability
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refers to the
fluctuations / variations of climate observed since the instrumental period
(i.e., 1860 to present). These fluctuations are due to natural causes and to
human activities.
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Season
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a division of
the year according to some regularly recurent phenomena, usually astronomical
or climatic. In the tropics, precipitation is the primary factor; thus,
nearly all regions have their rainy season and dry season.
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(climatological normal) |
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the average
value of a meteorological element over any fixed period of years that is
recognized as standard for a country and element concerned; usually a 30-year
period as recommended by the World Meteorological Organization (WMO).
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Anomaly
(departure from normal) |
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the deviation
of (usually) temperature or precipitation from the normal values in a given
region over a specified period.
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NE Monsoon
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locally known
as "Amihan". It affects the eastern portions of the country from
October up to late March, starts over
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SW Monsoon
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locally known
as "Habagat", it affects the country from July to September, is
very warm and humid, occurs when warm moist air flows over the country from
the southwest direction, is characterized by heavy rainfall that may last for
a week. It brings the rainy season to the western portion of the country.
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Linear Systems
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Description
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Associated Weather
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Period
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Intertropical
Convergence Zone (ITCZ)
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Result of the northern
hemisphere and southern hemisphere tradewind convergence
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Widespread cloudiness,
occasional thunder-storms, precipitation, moderate to strong surface winds
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Migratory, depending on the
time of the year
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Tail-end of Cold Front
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Front boundary of 2 air
masses, found in mid-latitudes
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Rainfall and cloudiness
over affected areas
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Northern portion of the
country during the Northern Hemisphere winter season
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Easterly Waves
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Wavelike perturbations
embedded in the easterly current
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cloudiness and
precipitation in eastern coastal portions
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More frequent during the
transition period
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Tropical Cyclone Intensity / Category
Intensity / Category
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Maximum Winds
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Tropical
Depression
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Between 35 KPH and
64 KPH near the center
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Tropical Storm
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Between 65 KPH and
118 KPH near the center
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Typhoon
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119 to 200 KPH near the center
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Super Typhoon
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Maximum winds greater that 200KPH
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Date of Download: Jan. 22, 2013