thermal wind

...This law of geostrophic winds is said to hold true almost entirely in the free atmosphere in areas with latitudes of 20 degrees or higher.
[thermal wind]
As shown in Figure 3-a, in the vertical air column of constant cross-sectional area between two isopressure surfaces, there is a certain amount of air corresponding to the pressure difference, so if the temperature rises, it expands and the distance between the isopressure surfaces becomes wider, and if the temperature drops, it contracts and the distance becomes narrower. From the gas state equation P = ρ RT ( P is atmospheric pressure, R is the gas constant, ρ is air density, and T is absolute temperature), we can see that the distance between two isopressure surfaces is proportional to the average air temperature (absolute temperature) between the isopressure surfaces at each location. …

*Some terminology explanations that mention "thermal wind" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…この地衡風の法則は緯度20゜以上の地域における自由大気においてほぼ成り立つといわれている。
［温度風thermal wind］
　図3-aに示すように，二つの等圧面の間の一定断面積の鉛直気柱の中にはその気圧差に相当する一定量の空気があるので，気温が高くなれば膨張して等圧面の間隔は広くなり，気温が低くなれば収縮して間隔が狭くなる。気体の状態方程式P＝ρRT(Pは気圧，Rは気体定数，ρは空気の密度，Tは絶対温度)から，二つの等圧面の間隔はそれぞれの場所において等圧面間の平均気温(絶対温度)に比例することがわかる。…

※「thermal wind」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報