Author: Marilyn M. Everest

PREVENT ERRORS CAUSED BY UNWANTED SKY RADIATION WITH THE “SKY-SPY”
(U.S. Patent No. 4,420,265)
ADVANCED AGRICULTUAL INFRARED
THERMOMETRY SYSTEMS
EVEREST’S INFRARED THERMOMETERS AND TEMPERATURE
SENSORS INCLUDE:
LIGHT SIGHTING - VARIABLE FOCUS – VARIABLE FIELD-OF-VIEW
AND “SKY-SPY” FOR DETECTION OF UNWANTED SKY RADIATION
DESIGNED EXCLUSIVELY FOR THE NATURAL ENVIRONMENT
EVEREST INTERSCIENCE
Physical Address: 1891 North Oracle Road • Tucson, AZ 85705-6444
Mailing Address: P. O. Box 5276 • Tucson, AZ 85703-0676
Phone: 520-792-4545 • Toll Free: 800-422-4342 • Fax: 520-792-4546 E-Mail: mmeverest@earthlink.net - Website: www.EverestInterscience.com

CAUSES OF GLOBAL WARMING ALSO PRODUCE ERRORS IN AGRICULTURAL TEMPERATURE MEASUREMENTS WITH INFRARED
THERMOMETERS
Infrared thermometers and temperature sensors, such as the AGRI-THERM II and the Series 4000 instruments, manufactured by Everest Interscience, have been used for a few decades now to measure the surface temperature of crop canopies and individual leaves in agronomic applications for the natural environmental sciences. This work has been done primarily for agricultural applications to determine optimum irrigation scheduling and conservation of water. Much work has been done by researchers in universities and federal facilities and in many foreign countries on such theories as the Crop Water Stress Index (CWSI) and Stress Degree Day (SDD) concepts. However, one important concept has often been overlooked in these studies. That is the effect of sky radiation and the employment of a means to compensate for the reflection of the sky from plants or other objects that the infrared thermometer is measuring.
The unique solution of the phenomenon of sky radiation is the addition of the Everest Interscience “Sky- Spy” to the infrared thermometer or temperature sensor. The Sky-Spy “… provides a novel means for sensing the level of infrared radiation received by the vegetation from a skyward direction,” according to Everest’s U. S. Patent No. 4,420,265. With this invention, a second detector is utilized wherein the reflection by the vegetation received from a skyward direction may be taken into account to measure the actual surface temperature of the plant. The purpose of this second sensor is to account for reflected sky radiation characteristics and compensate for them in the temperature reading from the plant itself in order to produce a more precise infrared measurement.
M. Fuchs and C. B. Tanner found that :
Infrared thermometers with a bandpass filter from 8 microns to 13 microns can be used to measure the real temperature of vegetal surfaces with errors in the range of 0.1C to 0.C. To do this the emissivity must be either known or determined and a correction accounting for the reflected radiation from the surroundings must be made. Values of emissivities found for dense canopies of alfalfa and of sudangrass were between 0.97 and 0.98. Emissivities of single leaves of snap bean and tobacco were 0.6 and 0.97, respectively. Depending on the radiation of the surroundings correction of +0.6C to +1.4C had to be added to the apparent radiative temperature of these surfaces in order to yield real surface temperature. AGRONOMY JOURNAL, 1966.
In order to explain the inaccuracies that can be derived by measuring the vegetation without the use of a “Sky Spy,” assume that the leaf that is being measured is a first surface mirror and that the temperature reflected by that mirror is the temperature of the radiation from the sky. This temperature could be as much as -80°C under clear sky conditions. Then, assume that the mirror affect is fading into the leaf and the mirror radiation comprises only 3.0% of the total radiation (Surface Emissivity = 0.97) and the leaf forms 97%. The secondary mirror radiation, or the temperature of the sky radiation reflected on the secondary mirror, is now only three (3.0) percent of the temperature of the radiation or -2.4°C. The temperature of a leaf is usually in a range of no more than plus/minus ten degrees compared to the surrounding ambient air. So, the -2.4°C could be twenty-four (24) percent of the total or as much as -2.4°C, bringing the effective temperature of the leaf down by that amount. In a science where accuracies of ±0.5°C are desired, this error is intolerable.
Of course, at low elevation conditions, perhaps in the presence of high water vapor and CO2 layers, the apparent sky temperature is much warmer than -80°C. Under these conditions, the Sky-Spy instantly and automatically corrects for all sky temperatures from ambient to -100°C or beyond. This unique Sky-Spy, coupled with the infrared thermometers for making SDD and CWSI measurements for irrigation purposes that is covered in Everest’s U. S. Patent No. 4,301,682, provide a more accurate means of making the precise temperature measurements needed for CWSI application. One such infrared thermometer is Everest’s AGRI-THERM II.
The AGRI-THERM II has been used extensively worldwide to measure crop canopy temperatures in an attempt to control irrigation with the goal of improving crop yields while reducing the amount of irrigation needed. More information on this subject can be read in M. B. Kirkham’s book, Principles of Soil and Plant Water Relations, 2004.
The AGRI-THERM II infrared thermometers are capable of taking surface temperature measurements in a highly dynamic environment such as having the thermometer taken from an air conditioned truck into the heat of the desert without giving them time for equilibration before taking the measurements. Under these environmental conditions, they respond with accuracy of ±0.5 degrees C or ±1.0 degree F.

HANDHELD DIFFERENTIAL INFRARED THERMOMETER SPECIFICATIONS
(U.S. Patent Nos. 7,377,158, 4,420,265 and 4,477,814)
MODEL 6110.4ZL and MODEL 6210.4ZL WITH EMBEDDED DATA LOGGER
TEMPERATURE MEASUREMENT
OPTICAL CONSIDERATIONS
OPERATING CONDITIONS
GENERAL
ELECTRICAL INTERFACE
EVEREST INTERSCIENCE
Physical Address: 1891 North Oracle Road • Tucson, AZ 85705-6444
Mailing Address: P. O. Box 5276 • Tucson, AZ 85703-0676
Phone: 520-792-4545 • Toll Free: 800-422-4342 • Fax: 520-792-4546 E-Mail: mmeverest@earthlink.net - Website: www.EverestInterscience.com
80620 6110.4ZL and 6210.4ZL Specifications
Printed in U.S.A.
.

ENHANCE YOUR INFRARED THERMOMETER’S PRECISION
WITH THE “SKY-SPY”
CAUSES OF GLOBAL WARMING
ALSO PRODUCE ERRORS IN INFRARED TEMPERATURE MEASUREMENTS IN AGRICULTURE!
ERRORS AS LARGE AS 2.0°C CAN BE THE RESULT OF SKY OR SURROUNDING RADIATION
EVEREST’S SKY-SPY (U.S. Patent No. 4,420,265) CORRECTS FOR ERRORS CAUSED BY RADIATION TO THE SKY
Plant leaves reflect approximately 2-4% of incident infrared radiation; normally this is a minor amount unless the radiative object is extremely cold, such as with sky conditions.
“Depending upon the radiation of the surroundings, corrections of +0.6 to +1.4°C had to be added to the apparent radiative temperature of these surfaces in order to yield real surface temperatures.”
Drs. M. Fuchs and C. B. Tanner, AGRONOMY JOURNAL, 1966
U. S. Patent Nos. 7,355,178, 4,777,814, 4,494,881 and 4,301,682

AGRI-THERM-II IRTS MEASURE THE TEMPERTURE OF THE…
TARGET
AMBIENT AIR
DIFFERENCE BETWEEN AMBIENT AIR AND THE TARGET
SKY TO CORRECT FOR UNWANTED SKY RADIATION

SERIES 4000 IR SENSORS ARE FIXED-MOUNTED AND CAN…
BE RUN CONTINUOUSLY
MEASURE SURFACE
TEMPERATURE OF TARGET
INCLUDE EMBEDDED DATA
LOGGER
MEASURE SKY TEMPERATURE TO CORRECT FOR UNWANTED RADIATION

Scale Range:	-40°C to 100°C or -40°F to 212°F
Resolution:	0.1°C or 0.1°F
Accuracy:	±0.5°C or 1.0°F
Repeatability:	±0.1°C or ±0.2°F
Temperature:	All Functions in °C or °F, Corresponding to Voltage Out
Noise Effective Temperature:	<0.1°C or °F
Temperature Measurement Modes:	Surface Temperature, Ambient Dry Bulb Air Temperature and Temperature Differential

Optical Configuration:	Robust, Aerospace-Quality, Double-Coated Zinc Selenide Optics per Military Specification MIL-C-13508
Spectral Pass Band:	8 < Wavelengths < 14 Microns
Sighting:	TTL/SLR Intra-Optical Light Sighting: Visible Light Illuminates Field of View / (U.S. Patent Nos. 4,407,179, 4,494,881 and 7,355,178)
Illumination Source:	Light Emitting Diode -- SAFE - NO LASERS!
Focus:	Variable from 4° to 20° down to 2 mm with VARIO-ZOOOM (U. S. Patent No. 7,377,158)
Display:	Numeric Liquid Crystal Display on Rear Panel

Operating Environment:	-20°C to 65°C or +14°F to 150°F, up to 99% Relative Humidity, Non-Condensing
Storage Temperature:	Same as Operating Environment Temperature

Response Time:	<1 Second
Emissivity Compensation:	Settable from 10% to 99% on Rear Panel
Operating Distance:	2 cm to Infinity
Warranty:	One-Year Limited Warranty on Parts and Labor
Sky Radiation Detection:	SKY-SPY Corrects for Errors Caused by Radiation to the Sky (U. S. Patent No. 4,420,265)
Embedded Data Logger:	Valitec Data Ready Data Logger; Stores up to 4 Million Records – MODEL 6210.4ZL ONLY

Power Sources:	Rechargeable Nickel Cadmium Rechargeable Batteries; Ten Hours Continuous Use on Full Battery Charge
Output Signal:	Standard: Analog Millivolt (-400 mV to 1000 mV at 10 mV/°C) / Optional: 4-20 mA, 0-5 Volt and Thermocouple Types J & K
Battery Charger:	120 Volt, 60 Hz 3W, 230 Volt, 50 Hz Optional