Download Clear Sky Calculator apk 2.1 free for Android smartphone

28 Sep
Clear Sky Calculator

Posted by Apogee Instruments in Business | Sept. 28, 2016 | 1 Comments

Apk file size: 3.4 MB

The Clear Sky Calculator is used to determine the need for recalibration of radiation sensors. It is most accurate when used near solar noon in the summer months. The calculator estimates the intensity of solar radiation (either total global shortwave radiation, measured by pyranometers, or global photosynthetic photon flux density, measured by quantum sensors) incident on a horizontal surface at any time of the day, at any location in the world. The equations used to estimate clear sky solar radiation with the Clear Sky Calculator come from the clear sky solar radiation model used to calculate net radiation in the ASCE Standardized Reference Evapotranspiration Equation ( The only input requirements to the calculator are site elevation, latitude, longitude, reference longitude, and air temperature and relative humidity measurements or estimates. These data are typically easy to obtain, making the Clear Sky Calculator a simple solar radiation reference that can be used to estimate pyranometer and quantum sensor accuracy and determine the need for recalibration.

When used near solar noon over multiple clear, unpolluted days during spring and summer months, accuracy of the Clear Sky Calculator is estimated to be ± 4 % in all climates and locations around the world. As an example, modeled incoming shortwave radiation (SWi) from the Clear Sky Calculator closely tracked measured SWi (data from a heated and ventilated Kipp & Zonen CM21 pyranometer) for a clear day (April 21, 2012) in Logan, Utah. The ratio of measured SWi to modeled SWi was between 1.00 and 1.05 (0 % and 5 %) from 9 AM to 6 PM (solar zenith angles less than 65°). The average ratio from two hours before solar noon to two hours after solar noon was 1.02 ± 0.01 (2 ± 1 %). (see )

A more detailed discussion of Clear Sky Calculator accuracy is given on the webpage (, where the necessary accuracy of the required inputs is discussed.

Apogee strongly encourages our customers to use the Clear Sky Calculator as an effective way to monitor pyranometer and quantum sensor performance and determine the need for sensor recalibration. If a sensor is consistently different from the Clear Sky Calculator by more than a few percent, please contact us about recalibration.

Whats new

    Version 2.1 - Fixed an issue with the longitude time zone.
    Version 2.0 - New features for ease of use.
    Version 1.3 - Minor bug fixes.
    Version 1.2 - Update for Lollipop compatibility.
    Version 1.1 - Small change for tablet compatibility.

Apogee Instruments part of our Business and have average installs from 1000 to 5000. Last Update Sept. 28, 2016. Google play rating is 95.0. Current verison is 2.1. Actual size 3.4 MB.

Download clear-sky-calculator.apk 3.4 MB


Shofiana Ifada

Light to save easy to use No need ultra fast internet connection, edge signal is enough to connect

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