Photography in the Dark (and Other Uses for New Camera Technologies)

Photography is a word originating from the Greek meaning  “drawing with light.”  The implication is that there must be sufficient light available to undertake the process. Since the dawn of the art (and science) of photography around 1827, the amount of light available in nature has remained the same (sunlight, moonlight, starlight, lightning), but the sensitivity of the medium upon which the light was “drawn” has steadily improved, and in recent years, almost at an exponential rate. Whereas the first photographs required exposures of many minutes in full daylight, current CMOS camera sensors offer ISOs routinely exceeding 400,000. They can almost “see in the dark” (at least using the human eye as a reference). Image intensification ups the ante even further, as does expanding beyond the visible into the UV and near IR portions of the spectrum, allowing capture of natural phenomena invisible to the unaided eye.  The temporal domain has also been enhanced. The snap shot gave way to movies and video at 24 to 30 fps. However, high-speed cameras now allow frame rates to tens of thousands per second. At the other extreme, time lapse video compresses time to highlight atmospheric dynamics. The explosion of interest in virtual reality is creating video capture systems that far surpass the fish-eye lens, proving literally 360 degree immersive viewing with minimal distortion. These new imaging technologies, obviously a boon for the creative and artistic communities, also have growing lists of applications within the atmospheric sciences, including lightning research and related fields, notably during nighttime hours.

            The discovery and investigation of sprites (dim lightning-induced mesospheric optical emissions at the edge of human visual perception) provides an example of the key role played by scientific imaging systems. The first sprite pictures were grainy, monochrome, low resolution videos using costly image intensified cameras. Today, prosumer cameras can capture real-time, full color sprite videos at 4K resolution.  Spectrally enhanced DSLR cameras have paved the way for low-cost mapping of convectively generated gravity wave modulations of the mesopause airglow layer, and their influence on the luminosity of lightning-induced elves. Documenting complex convective storm-top dynamics with high resolution time lapse video at night (as well as during the day), when combined with the increased temporal/spatial resolutions of GOES-R satellite mapping, will shed new light on processes such as cloud top gigantic jets and irreversible tropospheric-stratospheric exchanges of greenhouse gases. High speed cameras continue to tease out details of the lightning discharge including those responsible for sprites, halos and elves. Nocturnal atmospheric phenomena as diverse as noctilucent clouds, moonbows, crespuscular rays, meteor trails and, of course, aurora, are becoming ever easier to document. Time lapse cloud videos are no longer restricted to the daylight realm. The more we watch (and photograph) - the more we will learn.