spektrivuorokaiden

Spektrivuorokaiden is a term used in speculative atmospheric science to denote a diurnal cycle in the spectral composition of daylight observed on a planetary body. The name blends Finnish spektri (spectrum) and vuorokausi (day), and is used to describe the daily pattern of spectral irradiance.

In this concept, the spectral power distribution E(λ,t) evolves over the course of a local day as solar geometry and atmospheric conditions change. Scattering and absorption by air molecules, aerosols, and ozone modify the proportion of light at different wavelengths, producing characteristic diurnal curves. At sunrise and sunset the spectrum tends to shift toward longer wavelengths, while near solar noon the direct component can be relatively richer in shorter wavelengths, depending on atmospheric clarity and aerosol load.

Measurement and use: Spectroradiometers and sun photometers record E(λ,t) across the visible and near-infrared. Analysts summarize spektrivuorokaiden with metrics such as the diurnal amplitude, the spectral shape index, and integrated irradiance in bands important for photosynthesis and solar energy.

Status: The term originates in fictional or theoretical literature and is not an established term in real-world meteorology. It is used in world-building and speculative science to explore how daily spectral patterns could affect climate simulations, plant biology, and architectural lighting. See also spectral irradiance, diurnal cycle, and radiometry.