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مباحث عمومی هواشناسی

وضعیت
موضوع بسته شده است.

Amir Mohsen

متخصص بخش هواشناسی
بر اساس آخرین اطلاعات رادیو سند فرودگاه مشهد:

میزان رطوبت سطح زمین 60 درصد

میزان رطوبت تراز 500 میلی بار: 80 درصد

میزان رطوبت تراز 700 میلی بار 45 درصد

میزان آبهای قابل بارش: 8.79

میزان شاخص K-Index : 10.50


1000 hPa to 500 hPa thickness: 5513.00
 

Amir Mohsen

متخصص بخش هواشناسی
انیمیشن مدل اسمبل

144 الی 240 ساعت آینده

u3907mlf3iites45u72p.gif

 

کدخدا

کاربر ويژه
درود

عراق زیر توپخانه دریا سرخ و مدیترانه!!!
ایا سیل در عراق خسارت خواهد زد؟
اگر بارشها 1000 کیلومتر شیفت کنه به سمت شرق چه خواهد شد؟

9pgooi3nujfv3d274ow.png
 

Amir Mohsen

متخصص بخش هواشناسی
متاسفانه این نقشه منطقه خاورمیانه رو نداره

جت استریم امروز:

hgt300.png


جت استریم 180 ساعت آینده که فوق العاده است:

hgt300.png
 

Amir Mohsen

متخصص بخش هواشناسی
The Jetstream and The Weather in the UK
In order to understand the jet stream you need to have some idea of what is occurring in the atmosphere nearest the ground; known as the troposphere. It is also helpful to understand the formation of Hadley, Ferrel and Polar cells and how The Coriolis Effect influences these tropospheric cells. The jet stream flows in both hemispheres around the earth, but for ease this article will consider the Northern Hemisphere only.

The jet stream is a strong flowing ribbon of air that flows around our planet high up in the atmosphere, at around the level of the tropopause. Situated between the troposphere and the stratosphere, the Jet Stream is approximately 11 kilometres above the surface of the Earth at the poles and around 17 kilometres above the surface of the Earth at the equator. The jet stream flows at around 160kmph (100mph). We often hear that the jet stream is responsible for influencing the weather in the UK, so it is natural to wonder what causes the jet stream and why it has such an influence on the weather we experience on the ground.

Jet streams form and are strongest where variable air temperature gradients are steepest. This is normally seen in two zones:
  • The boundary between the polar and mid latitude air . The Polar Front Jet or Polar jet
  • The boundary between the mid latitude air and tropical air . The Subtropical Jet.
Both these jets are separate entities but they can join up from time to time across an area of the earth. The polar jet is the strongest as the temperature gradient across Polar and mid latitude regions is greatest. This is increased again in the Northern Hemisphere during winter. Both the subtropical jet and the polar jet travel from west to east and both would travel uniformly and evenly around the earth if it wasn.t for other influencing factors.

See Fig 1. below for an example of a typical jet stream chart across the earth.
Typical JetStream
jet1.png

Click to enlarge
Fig 1: The jet stream is shown in red at its strongest point fading to yellow at its weakest. The STJ is the area where the subtropical jet is flowing, the PJ is an area where the polar jet flows and the P&STJ shows where the jet streams have combined.

Influencing factors on the Jet Stream flow
The factors that influence the flow of the jet stream are the landmasses and the Coriolis effect. Landmasses interrupt the flow of the jet stream through friction and temperature differences, whilst the spinning nature of the earth accentuates these changes. So the jet stream meanders across the earth, like a river meanders before it reaches the sea. The meandering sections of the jet stream continue to change as they interact with landmasses once again, creating an ever-changing state of flux and subsequent temperature differences.

In winter the temperature of the stratosphere can also have an effect on the strength and position of the jet stream. The cooler the polar stratosphere, the stronger the polar/ tropical differential becomes; encouraging the jet stream to gain in strength. The warmth of the landmasses and oceans (such as the El Nino Southern Oscillation) can also have a bearing on the strength and amplitude of the jet stream.

Jet Stream Variables
The strongest areas of the jet stream are known as jet streaks. These are areas where the jet stream has increased in speed by as much as 100kmph. A typical jet streak is 160km wide, 2-3 km thick and lasting several hundred km in length. The strongest jet streams are seen where the upper air temperature differentials are greatest, the weakest jet streams appear when the opposite is true. Strong jet streams tend to have very little meandering associated with them whereas weaker jet streams have a considerable amount of meandering associated with them.

A Summary of the Jet Stream
  • Jet streams are strong upper air currents circumnavigating the globe.
  • There are two main jets: the polar jet and the subtropical jet.
  • Jet streams can fluctuate in strength between 100-200mph.
  • The jet stream meanders in waves.
How does the jet stream affect the weather in the UK?
To try explain how the jet stream affects the weather in the UK, it is worth going back to the jet stream chart seen in Fig 1, now zoom in to the jet stream analysis over the Atlantic as seen in Fig 2.
Jet Analysis
jet2.png

Click to enlarge
The jet stream is shown in pink at its strongest point fading to yellow at its weakest. CA=cold polar air, WA=warmer air, PJ=polar jet, STJ=subtropical jet, JS=jet streak.

From Fig 2. you can see that the polar front jet meanders across the country in a wave like pattern. These waves introduce pockets of colder air southwards and warmer northwards. The temperature change is demonstrated by looking at the air temperature at a high enough altitude in the atmosphere, where ground and sea temperatures do not affect it .around 1500 metres in altitude where the air pressure is around 850 hPa.

Fig 3. shows how these temperatures match the fluctuations in the jet stream.
Jet + 850hpa Temps
jet3.png

Click to enlarge
From looking at Fig 3 and the 850-hPA temperatures you can see the clear boundaries between the cold and warm air masses, which is being divided by the polar jet. You can also see the demarcation between warm and hot air that the sub tropical jet is demarcating. This demonstrates the pattern of the jet stream, showing how it is linked to and by the difference in warmer and cooler air masses.

Furthermore, looking back at FIG 2, the wave pattern associated with the polar jet has distinct peaks (ridges) and troughs. It is no surprise to find that when we overlay the jet stream with a chart showing sea level pressure, that the ridges occur where sea level pressure is highest and the troughs occur where sea level pressure is lowest (as FIG 4 demonstrates). This is because air rises where troughs are situated and sinks where ridges are occur. Rising and sinking parcels of air will therefore determine the type of weather that a region experiences.
Ridges and Troughs
jet4.png

Click to enlarge
R=ridge, T=trough, X=deep sea level depression or low.

Look at the area X on Fig 4. which is situated towards the west of Iceland. This is a common cyclonic or baroclinic depression that is caused by the difference in pressure and temperature over a region. This is feeding strength to the jet stream, which is then invigorating the depression.

In contrast, Fig 5 shows the same chart from FIG 2. However, note the following points:
  • The circled area is where the jet stream is strongest . the jet streak.
  • The purple box marks the winds entering the jet streak.
  • The winds leaving the jet streak are marked by the black box.
The winds leaving the jet streak are rapidly diverging, creating a lower pressure at the upper level (tropopause) in the atmosphere. The air below rapidly replaces the upper outflowing winds. This in turn creates the low pressure at the surface (marked X on fig 4). This surface low pressure creates conditions where the surrounding surface winds rush inwards. The Coriolis effect creates the cyclonic rotation that is associated with depressions. The strongest surface winds in any developing depression are normally seen at the left exit point of the jet streak, where the jet streak is strongest.
Jetstreak
jet5.png

Click to enlarge
Fig 5: The black oval indicates a jet streak, the purple square indicates entry winds into the jet streak and black box indicates rapidly diverging exit winds.

The positioning and strength of the jet stream determines where ridges and troughs are associated and this in turn influences the surface weather.

Zonality and Meridional flow.
During periods when the jet stream is flat and strong with little amplification or meandering, the UK is likely to experience weather that is driven straight in from the Atlantic. This is characterized by wet and windy weather with temperatures near to average. This condition is often termed .zonality. as the warm and cold air masses are clearly defined by a straight fast flowing jet.

During periods when the jet stream is amplified (such as Fig2) the pattern will be different. This is often termed meridional with polar air travelling further south than usual and warmer sub tropical air travelling further north. The exact positioning of the amplification of the jet stream will determine whether or not the UK is in cold polar air or warmer air from lower latitudes. If a meridional pattern becomes stagnant then the UK may experience either of these conditions for a period of time and the pattern may be known as .blocked..

Summary of the Jet Stream and the weather it creates:
  • The position of the jet stream over the UK determines the type of weather we experience.
  • If the polar front jet is situated significantly to the south of the UK we will experience colder than average weather.
  • If the polar front jet is situated to the north of the UK we will experience warmer than average weather.
  • If the polar front jet is situated over the UK we will experience wetter and windier than average weather.
  • If the polar front jet has a large amplification then cold air will travel further south than average and warm air will travel further north than average.
  • The direction and angle of the jet stream arriving at the UK will determine what source of air (i.e. cold, dry, warm, wet, from maritime or continental sources) the UK experiences.
Article written by Ed O'Toole
 

aznavar

کاربر ويژه
درود دوستان:گل:
گزارش امروز صبح آقای اصغری
مجری:سلام آقای اصغری چرا هوا گرم شده؟
اصغری:جرات میخواد روی آنتن اینو بگم خدارو شاکرم ک کشور 4 فصل بلکه 12 ماهی رو داریم
من: :ا در ادامه :52:
 

کدخدا

کاربر ويژه
درود دوستان:گل:
گزارش امروز صبح آقای اصغری
مجری:سلام آقای اصغری چرا هوا گرم شده؟
اصغری:جرات میخواد روی آنتن اینو بگم خدارو شاکرم ک کشور 4 فصل بلکه 12 ماهی رو داریم
من: :ا در ادامه :52:

درود سجاد جان:گل:

خب راست میگه بنده خدا 4 قصل در کشور به 12 فصل تبدیل شده :15:
کم کم تبدیل میشه 48 فصل:16:
 

ماهان.

کاربر ويژه
ارتفاع برف در ماگدبورگ به 7 سانتیمتر رسید، میزان بارش 3.6 میلیمتر و حدودن 5 سانتیمتر بود

دمای فعلی 4- درجه‌ست.

الان برف لایت شده، اما با عبور شاخه‌ای از همین موج، از چند ساعت دیگه دوباره تشدید بارش رو داریم

DSC_0418.jpg
 

aznavar

کاربر ويژه
درود سجاد جان:گل:

خب راست میگه بنده خدا 4 قصل در کشور به 12 فصل تبدیل شده :15:
کم کم تبدیل میشه 48 فصل:16:

:خنده2:
برام سوال شده چرا هیچوقت جواب درستی نمیده
متاسفانه لا ب لای حرفاش ب زبان عامیانه این منظور رو رسوند که دیگه هوا داره گرم میشه آخ چون داره بهار میشه:خنده2: و در ادامه گفت:حالا شاید در هفته های آتی هوا خنکتر بشه= دمای بالاتر از نرمال
 

کدخدا

کاربر ويژه
:خنده2:
برام سوال شده چرا هیچوقت جواب درستی نمیده
متاسفانه لا ب لای حرفاش ب زبان عامیانه این منظور رو رسوند که دیگه هوا داره گرم میشه آخ چون داره بهار میشه:خنده2: و در ادامه گفت:حالا شاید در هفته های آتی هوا خنکتر بشه= دمای بالاتر از نرمال

اصغری استاد پیچوندنه.
چیزی که خیلی زجراوره دما بالاتر از نرمال و بارش کمنر از نرمال
حالا اگه برعکسم نمیشد حداقل با هم یکی میشدن خیلی بهتر بود.مثلا جفتشون بالاتر از نرمال
 

mehrdad_teh

متخصص بخش هواشناسی
شرکت گاز گفت با توجه به افت دما و فراگیری سرما در کشور در مصرف گاز صرفه جویی کنید!!!

نکنه من الان دارم جایی غیر از ایران زندگی می کنم!؟
 

mehrdad_teh

متخصص بخش هواشناسی
شرکت گاز گفت با توجه به افت دما و فراگیری سرما در کشور در مصرف گاز صرفه جویی کنید!!!

نکنه من الان دارم جایی غیر از ایران زندگی می کنم!؟
 

آرش-مشهد

کاربر ويژه
سلام دوستان خدا رو شکر آبدیت نقشه ها خیلی خوب شدن. ان شا الله که این روند ادامه داشته باشه. (البته میدونم هنوز برای جو گیر شدن زوده -:))))

جدیدترین پیشبینی نروژ برای روزهای آتی مشهدالرضا (ع):

Tuesday22 JanuaryWednesday23 JanuaryThursday24 JanuaryFriday25 JanuarySaturday26 JanuarySunday27 JanuaryMonday28 JanuaryTuesday29 JanuaryWednesday30 January
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0 mm precipitation per 24 hours0 mm precipitation per 24 hours0 mm precipitation per 24 hours0 mm precipitation per 24 hours0 mm precipitation per 24 hours0 mm precipitation per 24 hours0 mm precipitation per 24 hours9 mm precipitation per 24 hours18 mm precipitation per 24 hours
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Long term forecast


برای امشب هم لطف کردن 0.2 میلیمتر بارش پیشبینی کردن که البته اصلا با نقشه های بسیار عالی که امیر محسن عزیز از آبدیت جدید نیروی دریایی گداشتن هم خونی نداره. امیدوارم بارش امشب هم غیر منتطره و خوب باشه:گل:

اینم برای فرودگاه مشهد:

Tuesday22 JanuaryWednesday23 JanuaryThursday24 JanuaryFriday25 JanuarySaturday26 JanuarySunday27 JanuaryMonday28 JanuaryTuesday29 JanuaryWednesday30 January
01d.png
04.png
01d.png
01d.png
01d.png
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03d.png
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14°10°10°12°12°17°
0 mm precipitation per 24 hours0 mm precipitation per 24 hours0 mm precipitation per 24 hours0 mm precipitation per 24 hours0 mm precipitation per 24 hours0 mm precipitation per 24 hours0 mm precipitation per 24 hours10 mm precipitation per 24 hours15 mm precipitation per 24 hours
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vindpil.0025.325.png
vindpil.0000.325.png
vindpil.0025.140.png
vindpil.0000.325.png
vindpil.0050.200.png
vindpil.0025.125.png
Long term forecast


برای فرودگاه هم امشب 0.6 میلیمتر بارش در نطر گرفته.
 
وضعیت
موضوع بسته شده است.
بالا