Overcast versus Obscured: What’s the difference?
In the GLOBE Clouds protocol and GLOBE Observer app, you can report if your sky is “overcast” or “obscured”. But what’s the difference? Below are some tips to help! All the photographs featured were collected by observers just like you - Thank you!
Obscured and overcast can be confusing, but when you understand what they mean, they make much more sense. Let’s start by defining them:
Overcast – The sky is completely covered by clouds (cloud cover greater than 90%). This means that you will see little or no blue sky. When it’s overcast, you are looking at stratus clouds. Stratus are gray or grayish white.
Obscured – Something is blocking your view of the sky AND the clouds. This could be dust, haze (pollution), smoke, volcanic ash, and even heavy rain or snow. Snow will appear white, but other obscurations may give the sky a brownish or orangish hue.
How to take photographs
Overcast – tilt your camera at 14 degree angle up at the sky. If you are using the GLOBE Observer app, the app assists you and automatically takes the photo when your device is titled at the right angle.
Obscured - look straight ahead at the horizon. The same way as when making visibility reports. If you are using the GLOBE Observer app, follow these steps to submit a photograph of the horizon. The example in these steps is for dust. Make sure to select the obscuration that you actually see (e.g., smoke, haze).
What if I see both?
An obscuration can be mixed with clouds. If the obscuration covers 30% or more of your view of the sky, then only report the obscuration observed. Use the steps above to take your photographs.