Estimates global solar radiation to determine the need for sensor recalibration
About Clear Sky Calculator
Clear Sky Calculator is a business app developed by Apogee Instruments.
How many times has Clear Sky Calculator been downloaded?
Clear Sky Calculator has been downloaded 6 thousand times. In the last 30 days, the app was downloaded 11 times.
What is the rating of Clear Sky Calculator?
Clear Sky Calculator has no ratings yet.
Is Clear Sky Calculator free?
Clear Sky Calculator is free to download. The APK download size is 5.43 MB. The latest version available is 2.8.1. The last update was on July 16, 2025.
What are the requirements for Clear Sky Calculator?
Clear Sky Calculator requires Android 4.0+ or higher. The app has a content rating of Everyone. The app has been available on Google Play April 2015.
Description
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 (http://www.kimberly.uidaho.edu/water/asceewri/index.html). 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 http://www.apogeeinstruments.com/using-the-clear-sky-calculator/ )
A more detailed discussion of Clear Sky Calculator accuracy is given on the webpage (http://clearskycalculator.com/model_accuracy.htm), 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.
Recent changes: Update for compatibility with Android 15
Get a detailed PDF report for Clear Sky Calculator with download trends, rating history,
and key performance statistics — useful for competitive research or tracking your own app.
Learn more
Are you the developer of this app? Join us for free to see more information about your app and learn how we can help you promote and earn money with your app.
Good for verification of par meter shows the accuracy make sure you're probed is level, so you get the proper reading
★★★★☆Shofiana Ifada· Aug 11, 2015
Light to save easy to use No need ultra-fast internet connection, edge signal is enough to connect
★☆☆☆☆Mad Tatter/ GH2KT· Jan 7, 2025
Not to be unfair for my job, to help others, I haven't used this severe to do my job. I look and listen to what's going on. I think I should put it to work for me, I don't know.
Google Play Rankings for Clear Sky Calculator
This app is not ranked
Technologies used by Clear Sky Calculator
5 permissions·2 libraries
Subscribe to see full permission and library details
Each subscription will automatically renew 3 days before the expiration date for
the same time period. Subscriptions can be cancelled at any time before the renewal.
