Seven laws. What is the sound of "beat" in the sentence "Jinsha water beats the clouds and cliffs warm" in the Long March? What does this sentence mean?

Jinsha River is warm in the clouds and cliffs, and Dadu Bridge is cold in the iron bars. "There is a couplet about water and the Red Army's conquest of water. The Red Army's forcible crossing of Jinsha River and Dadu River is of great significance in the history of the Long March. The Jinsha River is wide and swift, and Chiang Kai-shek dreamed of using this natural danger to panic in the Sichuan-Yunnan-Guizhou border region of the Red Army. 1935 In May, the Red Army skillfully crossed the Jinsha River. If crossing the Jinsha River skillfully is the cleverest and most successful battle of the Red Army in strategy and tactics, then crossing the Dadu River forcefully is the bravest and most tenacious battle of the Red Army. Dadu River is as dangerous as Jinsha River, and the enemy is heavily guarded. The cunning enemy also tore down the boards of the Luding Bridge on the river, leaving only thirteen iron cables. However, the heroic Red Army braved the enemy's bullets and broke through the Dadu River, crushing Chiang Kai-shek's plot to make the Red Army a second Shi Dakai. Therefore, the battle written in these two sentences has typical significance. The two sentences "Wuling" and "Wumeng" directly show the heroism of the Red Army through their subjective feelings, and these two sentences record stories through writing landscapes and show the heroic deeds of the Red Army through records.