ATtention this is your flying pilot speaking, Flight Environment PREVAILING WINDS https://www.weather.gov/source/zhu/ZHU_Training_Page/winds/Wx_Terms/Flight_Environment.htm Tropopause and lower stratosphere https://www.atoptics.co.uk/highsky/htrop.htm From the The Environmental Literacy Council - Air Mass & Pressure https://enviroliteracy.org/air-climate-weather/weather/air-mass-pressure/ "Why Is It So *&%# Cold? Come Warm Up In The Answer Vortex" Chuckle. Life-long learning. Hope all every one here knows in the coldest regions is ok. Last i heard 7 deaths. That sucks.