valkeassa
Valkeassa is the inessive singular form of the Finnish color adjective valkea, meaning white or pale. It is used to describe something that is located inside or within a state of whiteness when the noun it modifies is in the inessive case. In standard modern Finnish, valkea is less common in everyday speech than the more neutral valkoinen, but valkeassa remains common in literary, historical, or dialectal contexts.
In Finnish grammar, adjectives agree with the nouns they modify in number and case. Therefore valkea appears
Usage and register: valkeaa, valkealle, or valkeassa appear across various cases, but valkeassa is most likely
See also: valkoinen, Finnish adjective declension, Finnish grammar.