1.
upper layer; upper stratum
The higher portion of a layered structure, whether physical (atmosphere, soil, water) or social (class, organization).
大気の上層は気温が低い。
The upper layers of the atmosphere have low temperatures.
上層部の管理職が会議に出席した。
Upper-level managers attended the meeting.
上層階級の生活は一般市民とは大きく異なっていた。
The lifestyle of the upper class was vastly different from that of ordinary citizens.
Used both for physical layers (atmosphere, soil, ocean) and metaphorical ones (social class, organizational hierarchy). The physical sense is common in science and weather reports; the social sense appears in discussions of class, management, and power structures.
COMMON COLLOCATIONS:
- 上層大気: upper atmosphere
- 上層部: upper echelon/division
- 上層階級: upper class
- 上層階: upper floor
SIMILAR WORDS:
- 下層: lower layer/stratum — the opposite
- 中層: middle layer
- 表層: surface layer — the outermost part, not necessarily the highest