Water colour

Higher green chromaticity means the water appears greener, which may accompany an algal bloom or another water-colour change. The solid line is the day's typical reading across the water cells the sun's position made usable; the dashed line follows their greener upper tail, which moves first when a bloom is patchy. Hover or select any marker to see that day's representative image.

A turbidity proxy: the red share of the water's colour, measured over the same cells as the headline panel. Values above zero mean the water appears more turbid than usual for the selected period; below zero, clearer. Suspended sediment raises red reflectance, so this tracks it — but it is a colour ratio, not an NTU measurement, and it has not been calibrated against one.

Shortwave radiation is the sunlight reaching the lough. Higher sun attenuation means less light is available for algal growth and that lighting may have a stronger effect on the colour seen by the camera.

Rain can wash nutrients, coloured runoff and sediment into the lough. Water-colour or turbidity changes may follow hours or days later.

Wind mixes the water, can lift sediment from the bed and can move surface blooms toward or away from the camera. Sticks point where the wind blows; length is speed.

Aligned peaks and dips help show whether greener or more turbid water follows sunlight, warm weather, rainfall, wind or a changing lough level. Each line has its own scale.

• A persistent rise in green colour can provide an early warning of bloom development, but it is not a direct chlorophyll or cell-count measurement. Check the daily images.
• Relative red chromaticity shows clearer or murkier water than normal for the selected period, not laboratory turbidity.
• These are relative apparent water colour, not calibrated reflectance, chlorophyll or cyanobacteria concentration. Comparisons are meaningful within a site over time, not between sites or against laboratory values.
• Which frames count is set by the site's published calibration, not by a control on this page. The method behind the headline panel is named under it.
• Weather and water-level panels show possible influences, not proof of cause. Unreliable images are omitted and gaps mean no suitable observation was available.