What is Cl (Chlorophyll index) and how does it work? The chlorophyll index (Cl) is applied to calculate the total amount of chlorophyll in plants. In general, this index contains two separate bands: CIgreen and CIred-edge. These bands are responsive to slight variations in the chlorophyll content and are consistent for most types of plants. Clred – reliable chlorophyll indicator In this case, we will focus on the application of CIred-edge, which is a narrow band in the reflective spectrum of plants between the conversion of red to near-infrared. CIred-edge is calculated using the red-edge (730 nm) band. The cellular structure of plants tend to reflect waves within this spectral range, resulting in more light being reflected; thus, the higher the reflection, the greener the area. How is Clred used and how can the data be interpreted? Generally, this index is utilized for monitoring of chlorophyll content and assessing photosynthesis in plants. Since photosynthesis products comprise 95% of the crop’s dry mass, it is necessary to monitor the photosynthetic activity of plants to prevent it from dropping in advance. Such an approach allows for identifying affected crop areas and respond in a timely manner so that the plants stay healthy. Let’s consider the use-case below: 49.59358°N 29.66257°E False colouring is applied with an aim to visualize data for effective analysis. The palette is currently being adjusted from red (naked soil) to dark green (healthy plants). Green indicates areas where vegetation develops better and the amount of chlorophyll is quite high; yellow and pale green are meadows or recently sown fields; orange and red are the harvested and/or ploughed fields.