ISCCP Cloud Optical Thickness Trends (1983-2017)

What You're Looking At

This page shows 34 years of satellite measurements tracking how cloud properties changed over time.

Cloud Optical Thickness (tau): This measures how "thick" or "dense" clouds are - essentially how much sunlight they block. Think of it like measuring how opaque a curtain is. A thin curtain (low optical thickness) lets more light through, while a thick curtain (high optical thickness) blocks more light.

What the graphs show:

• Cloud Cover: What percentage of Earth is covered by clouds - this has been measured continuously since 1983
• Optical Thickness: How dense/thick the clouds are - increased 21% from 1983 to 2017
• Temperature: Cloud top temperature, which tells us how high the clouds are (colder = higher altitude)
• Pressure: Cloud top pressure, another indicator of cloud altitude (lower pressure = higher altitude)
• Water Path: Total amount of water in the cloud column

Key Finding: These measurements directly refute claims that satellites don't track cloud thickness, time of day, season, or trends over time. ISCCP has been measuring all of these factors continuously since 1983.

The 21% increase in optical thickness from 1983 to 2017 means clouds became significantly more effective at blocking solar radiation.

Data Source: NOAA ISCCP D2 Dataset