تحقیقات کاربردی علوم جغرافیایی

تحقیقات کاربردی علوم جغرافیایی

آغازگری همرفت

نویسندگان
زهرا قصابی
هوشنگ قائمی
پژوهشگاه هواشناسی و علوم جو
10.61186/jgs.25.76.16
چکیده
ساختار همرفت مرطوب ژرف می‌تواند تحت تأثیر چینش باد، انرژی پتانسیل در دسترس همرفتی، رطوبت نسبی و توزیع قائم هر یک از این متغیرها در کنار سایر عوامل مؤثر دیگر قرار گیرد که در این بین چینش باد نقش مهم‌تری در ایجاد همرفت ایفا می‌کند. این امر به سبب فرآیندهای بزرگ و همدید مقیاس، همراه با تعدیل انرژی پتانسیل در دسترس همرفت و بازدارنده همرفت، شرایطی مناسب برای ایجاد همرفت به وجود می‌آورند. نقش میانگین بزرگ‌مقیاس، سبب کاهش بازدارنده همرفت می‌شود، ولی سرعت قائم حتی چند سانتی‌متر بر ثانیه می‌تواند تأثیر آشکاری بر گمانه‌زنی محیط داشته باشد. همچنین وجود ناپایداری پتانسیلی معمولاً عاملی مهم در آغازگری همرفت مرطوب ژرف به شمار می‌رود. دیده می‌شود هنگامی‌که دما به نقطه بحرانی می‌رسد و بازدارنده همرفت حذف می‌گردد، همرفت ژرف مرطوب آغاز می‌شود. در حالتی‌ که بسته‌هوایی که از فراز لایه‌ پایدار کم ارتفاع زیرین بالا می‌رود، ممکن است دارای انرژی بازدارنده همرفتی نسبی کم و انرژی پتانسیل همرفتی آزاد نسبی زیاد باشد. این امر سبب پشتیبانی همرفت مرطوب ژرف ارتفاع یافته می‌شود. توده هوای گرم، آغازگری جریانات بالاسو را تداوم می‌بخشد و تکوین بعدی همرفت به فراسنج‌هایی مانند چینش باد قائم و کلاهک وارونگی محیط در کنار سایر فراسنج‌ها، بستگی دارد. سامانه‌های بزرگ‌مقیاس همرفتی می‌توانند با واداشت‌های کمتری سبب بالاروی گسترده توده هوا بر روی سطح جبهه تا تراز همرفت آزاد شوند
کلیدواژه‌ها
همرفت مرطوب ژرف
آغازگری همرفت
انرژی پتانسیل همرفتی
بازدارنده همرفت

عنوان مقاله English

Convection initiation

نویسندگان English

Zahra Ghassabi
Hoshang Ghaemi
چکیده English

The structure of deep moist convection can be influenced by various factors, including wind shear, available potential energy of convection, relative humidity, and vertical distribution of these variables. Among these factors, wind shear plays a more significant role in the creation of convection. The interaction between large-scale and synoptic-scale processes, along with the adjustment of available potential energy for convection and the presence of convection inhibitors, creates conditions suitable for the development of convection. The large-scale average reduces the convection inhibitor, while even small vertical velocities, such as a few centimeters per second, can have a noticeable impact on the environment's sounding. The presence of potential instability is also considered an important factor in initiating deep moist convection. When the temperature reaches the critical point and the convection inhibitor is removed, moist deep convection begins. If an air parcel rises above the lower stable layer with low relative convective inhibition energy and high relative free convective potential energy, it supports the development of deep moist convection. The initiation of updrafts by warm air masses and the subsequent development of convection depend on parameters like vertical wind shear and the inversion cap of the environment, among others. Large-scale convective systems can be triggered with less forcing due to the significant uplift of the air mass from the surface to the convection level along the front.

کلیدواژه‌ها English

Deep moist convection
convection initiation
potential energy of convection
convection inhibition
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