Ultraviolet and infrared cameras help perform a type of science called spectroscopy that can detect chemical signatures of gases without physically collecting those molecules. (More on this here.) When atmospheric gases are excited by radiation like sunlight, their molecules become excited and vibrate, releasing energy in unique and specific wavelengths that we can use to "fingerprint" atmospheric gases, just like our eyes use colors to help us identify objects in the visible range. On Juno, spectroscopic photographs taken by JIRAM and UVS will help determine the atmospheric composition both deep into the atmosphere and in Jupiter’s aurora (specifically, H 3 + molecules).

Radiometers are also kind of like a one-dimensional, single-pixel camera with a flash (bear with me here). When you photograph an apple with a flash, you send a pulse of white light to the apple. The apple absorbs some of the light and reflects some of it back to you. The color of the light that gets reflected gives you useful information about the apple: is it green, or red, or maybe rotting and not safe to eat? A microwave radiometer does something similar: it sends out a pulse of radiation in the microwave band of the electromagnetic spectrum (with wavelengths of 1 to 1000 millimeters), and records the return information. The radiometer records the delay and intensity of the return radiation. Microwaves are useful at Jupiter because they can penetrate clouds. On Juno, the Microwave Radiometer (MWR) tells us about the deep structure of Jupiter by measuring the return time and intensity of microwave pulses in six specific frequencies. This tells us the quantity of water, ammonia and temperature at different levels in the atmosphere, improving our understanding of Jovian dynamics and, more generally, the planetary dynamics of gas giants.

At the end of the day, scientists are relying on images and cameras of all sorts to do the critical science of Juno, seeing everything from the internal structure of storms and flow within Jupiter’s upper atmosphere to the composition and mass of the deep interior.

More reading/watching:

NASA's Juno Mission Information Page

Wikipedia: Microwave Radiometer

Dr. Fran Bagenal explains the current state of knowledge on Jupiter as well as Juno’s science goals (12:05 for the science objectives specifically)

Great explainers on Juno's instruments