Observe and Report
NEVER look directly at the Sun!
Students observe which types of clouds are visible, how much of the sky is covered by clouds, and the opacity of clouds. They also report on surface and sky conditions, information complementary to the satellite view.
Reminder: This protocol includes a category of “No Clouds” which should be reported whenever there are no clouds visible in the sky. A “No Clouds” report is just as important as a “Clouds Observable” report in helping understand our Earth’s system. If “Clouds Observable” is reported, follow the observation hints located in the left navigation column.
Cloud observations can be taken at any time! This Protocol is designed to be flexible and fit into your schedule, classifying, observing, and reporting cloud observations when it works for you.
|* Best||Corresponding to satellite observation (within +/- 15 minutes of orbiting satellites)|
|Better||Within one hour of local solar noon|
But!...The value of the NASA collaboration is the ability to match your ground observations to corresponding satellite data.
Latitude/longitude location and time zone are key to overpass calculations. As a GLOBE Teacher you will need to enter your latitude, longitude and time zone when you use the overpass tool, as an individual Citizen Scientist you will be entering your latitude, longitude and time zone when you log into the GLOBE Observer app for the first time and each time you move observation locations. You can always verify your location using Google Earth (download of the Google Earth Tool). It is also important to know if you are currently observing Daylight Saving Time when calculating overpass times.
GEO data Matches:
There is no need to request an overpass schedule for Geostationary (GEO) satellites. Geostationary (GEO) data is gathered and processed almost every 30 minutes, therefore observations at almost any time of day have a good chance of being matched to GEO satellite data. Since GEO data comes from different satellites, match times will vary from one ground location to another. Once you receive matches, look for patterns in observation time to determine when best to observe.
CERES data Matches:
To match CERES data, we ask that you make your cloud observations within +/- 15 minutes of your overpass schedule, meaning the passage of a CERES instrument over your part of the world. This is because clouds change on the timescale of minutes. The CERES instrument rides on two satellites that we match to, Terra and Aqua. The Terra overpass is in the morning, generally between 10 am and noon. The Aqua overpass is in the afternoon, generally between 1 and 3 pm.
CALIPSO data Matches:
The CALIPSO satellite sees only a small sliver of the Earth on each orbit, so the times returned by the overpass schedule are less frequent and there are some sections of the Earth in which images are not produced.