題目: Could station pressure ever exceed sea-level pressure? Explain.
打錯題目了 是這題:why is the difference in surface wind speed between morning and afternoon typically greater on a clear，sunny day than on a cloudy ，overcast day ?
- 5 年前最佳解答
why is the difference in surface wind speed between morning and afternoon typically greater on a clear，sunny day than on a cloudy ，overcast day ?
On a clear, sunny day, the surface and adjacent air is heated more by the sun than on a cloudy day, causing a thicker layer of unstable air near the surface. This thicker unstable layer leads to more extensive mixing with air in higher layers than on a cloudy day. Since the greater horizontal momentum in higher layers is preserved as that air is mixed with lower layers, and since that greater horizontal momentum is manifest as higher surface wind speed, that speed is greater in the afternoon (when mixing typically reaches a maximum) on a clear day than on a cloudy day.
在晴朗陽光燦爛的日子，空氣中水蒸氣都會吸收陽光的熱能，相較的陰天裡空氣中的水蒸氣溫度較低。而熱天裡水蒸氣會在空氣表面形成一層不穩定的厚氣層， 這層厚氣層會與高海拔的空氣層更緊密的混合。而高海拔中的橫向動量帶著空氣層與底層空氣層互相混合，形成高表面風速(空氣相互混合時處於最高峰）。而高海拔風速強度在晴天的中午時分處在高峰， 所以相較之下，比起陰天/雨天，晴天中午時候高海拔的風速也是最大的。