Climatic Data Elements

CLIMATIC DATA ELEMENTS:
A climatic data element is a measured parameter which helps to specify the

climate of a specific location or region, such as precipitation, temperature, wind
speed and humidity. Descriptive terminology for climatic data elements are:
Element Name - The full description of the element being referenced at the
climate station (e.g., maximum temperature).
Element ID - Is a shortened identifier for the element, usually 4 characters in

length (e.g., TMAX (maximum daily temperature), TMIN (minimum daily
temperature), PRCP (precipitation, etc).
Element Duration - The interval between measurements of a data element.

Common data element durations available for the station could include monthly,
daily, or hourly.
Statistical analysis of climatic data generates descriptive
information which reflects the average atmospheric conditions
at a location, as well as generating probabilities that extreme
events will occur. Any statistical analysis of climatic data, due
mainly to the limited number of samples available, must follow
the rules for statistical analysis. An important rule governing
small sample analysis requires a minimum of 30 samples.
This does not mean that climatic data with less than 30 years
of data cannot be analyzed, but that some adjustment be
made to estimate what a 30 sample set would produce.
Air Temperature
Temperature is a measure of the hotness or coldness of air. It is

measured on some definitive temperature scale. Two scales are
commonly used. The Fahrenheit and Centigrade temperature scales
establish the freezing of water at 32/0 degrees respectively and boiling
point at 212/100 degrees respectively. The Fahrenheit scale is used
most frequently in the US and Centigrade throughout the rest of the
world. Air temperature is usually measured with either a liquid-in-glass
maximum and minimum thermometer mounted in a vented, wooden
box or with an electronic sensor.
It is important that thermometers be shaded from sunlight to avoid an

erroneously high measured temperature. Instrument shelters are
designed to rectify this problem.
Evaporation
Evaporation is the physical process by which a liquid is

transformed to a gaseous state. Evaporation is influenced by
solar radiation, air temperature, vapor pressure, wind, and
possibly atmospheric pressure. Evaporation varies with
latitude, altitude, season, time of day, and sky condition.
Accurate evaporation readings requires careful maintenance
of an evaporation pan which contains water. The water
depth is measured daily and adjusted for any precipitation
which may occur.
Precipitation
Precipitation refers to all forms of water, liquid or solid,

that fall from the atmosphere and reach the ground.
Precipitation includes, but is not limited to, rain, drizzle,
snow, hail, graupel, sleet, and ice crystals. It is one of the
most basic data elements collected by any climate
station. Dew, frost and rime are excluded, since they are
a result of water vapor in air condensing or freezing onto
a surface.
Soil Temperature
Soil temperature measures the hotness or coldness of soil. Soil

temperature is very important to the agricultural industry. Most
seeds require a certain soil temperature in order to germinate. Soil
temperatures are commonly measured at 2, 4, 8, 20, 40, 60, and
120 inches with the 4-inch reading being the most frequently
observed.
Readings are usually observed and recorded daily. Maximum,

minimum, and current temperatures are generally recorded above 8
inches. At greater depths, where temperature changes more slowly,
only the current temperature is normally recorded. Different species
of plants have specific soil temperature ranges in which they will
grow.
Solar Radiation, Incoming
Incoming solar radiation is the total electromagnetic radiation emitted

by the sun striking the earth. Much solar radiation is absorbed by air
molecules, reflected back into space, or refracted as it passes through
the atmosphere. A pyrheliometer measures the direct solar radiation
that passes through the atmosphere unimpeded. It consists of an
enclosed radiation sensing element with a small aperture through
which the direct solar rays enter. A pyranometer measures the
combined incoming direct solar radiation and diffuse sky radiation. It
is mounted such that it views the entire sky. Both instruments can be
connected to electronic recording devices to collect the
measurements. Solar radiation sensors must be cleaned regularly
and exposed properly to accurately measure solar radiation.
Wind
Wind is the motion of air relative to the surface of the earth.

Wind speed and direction, the two primary elements, are usually
measured with an anemometer and wind vane, respectively.
Wind speed is generally measured in miles per hour; direction is
measured in degrees to the nearest ten(s) (10 to 360) with 360
degrees being north, 90 degrees being east, 180 degrees
representing south, and 270 degrees being west. Wind
measurement accuracy is primarily influenced by sensor height
and nearby objects.
https://www.nrcs.usda.gov/wps/portal/wcc/home/climateSupport/
fieldOfficeGuide/climaticDataElements

Climatic Data Elements

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CLIMATIC DATA ELEMENTS:

A climatic data element is a measured parameter which helps to specify the

Element ID - Is a shortened identifier for the element, usually 4 characters in

Element Duration - The interval between measurements of a data element.

Temperature is a measure of the hotness or coldness of air. It is

It is important that thermometers be shaded from sunlight to avoid an

Evaporation is the physical process by which a liquid is

Precipitation refers to all forms of water, liquid or solid,

Soil temperature measures the hotness or coldness of soil. Soil

Readings are usually observed and recorded daily. Maximum,

Incoming solar radiation is the total electromagnetic radiation emitted

Wind is the motion of air relative to the surface of the earth.

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