Low water clouds in the IR-HRVIS RGB are depicted in white colours. Water droplets strongly reflect short wave solar radiation, hence the strong intensity of the red and green colour beam. IR10.8 often shows lesser intensities for the blue colour beam; therefore the whitish tone can turn into yellow. Especially in winter season, low stratus and fog depict in yellow tones. Notice that the intensity of the blue colour beam intensifies with decreasing temperatures.
The image below shows ship trails over the Atlantic. Water in the exhaust from cargo vessels condensates and forms long trails. These low level water clouds can be seen in the IR-HRVIS RGB.