Day and Night Microphysics

29 Jan,2024 Download Pdf 3 Min Read

Indian Meteorological Department (IMD) has been issuing alerts with maps from various weather monitoring satellites.

Day and Night Microphysics RGB Imager

It is image created by combination of Red, Green and Blue colours.
Aim – To study various atmospheric characteristics.
Radiometer – A device that measures the properties of radiation by studying the radiation’s interaction with matter.
Atmospheric sounders – A devices that measure temperature, humidity and study water vapour as a function of their heights from the ground.
Factors determining RGB imager – Solar reflectance and brightness temperature.
Applications - It helps in analysis of different cloud types, initial stages of convection, maturing stages of a thunderstorm, identification of snow area, and the detection of fires.
It also helps in tracking the formation, evolution and depletion of cyclones and other weather events.

Solar reflectance is a ratio of the amount of solar energy reflected by a surface and the amount of solar energy incident on it.

Brightness temperature is the relationship between the temperature of an object and the corresponding brightness of its surface.

Daytime Microphysics (DtMicro) RGB – It is the data formed by combining information about the cloud brightness, cloud particle phase and size, and cloud top temperature.
Aim – To distinguish ice from water phase and to monitor the development of convection, fog and low clouds.

Solar Reflectance Recorded by INSAT 3D
Wavelength	Colour beam	Relates to
0.5 µm (visible radiation)	Red colour	Cloud thickness and amount of cloud water and ice
1.6 µm (shortwave IR radiation)	Green colour	Cloud particle size and phase
10.8 µm (thermal IR radiation)	Blue colour	Temperature

Observations – Water cloud is more reflective than ice cloud and have a stronger red beam, smaller water or ice particles have a higher reflectivity, resulting in a stronger green beam and warm surface corresponds to strong blue beam component.
Night microphysics – It is designed for monitoring the evolution of night time fog and stratus clouds.

Colour band	Determining factors
Red	Difference between 2 Thermal IR
Green	Difference between Thermal IR and a middle IR
Blue	Strength of 1 Thermal IR signal

Observations – A strong red beam for thick clouds, strong green beam for water clouds with small droplets and a strong blue beam for warm surfaces.

The Kalpana 1 and INSATs 3A, 3D, and 3DR satellites have bolstered India’s weather monitoring and warning services.