The aqueous bromothymol blue solution act as a pH indicator and turns blue only in case when the pH of the sample is above or equal to 7.6
Since the pH of the water at the surface of the lakes is higher and ranges between 7.5 to 8.5 the color of bromothymol turn blue.
The Doppler radar used in weather forecasting measures the direction and speed, or velocity, of objects such as drops of precipitation. This is called the Doppler Effect and is used to determine whether movement in the atmosphere is horizontally toward or away from the radar, which aides in weather forecasting.
They should be limited to suit your needs not overdoing it or underdoing just to a healthy weight.