Wednesday, December 26, 2012

Northern Cold

Much of the Northern plains of India have had extremely cold days on 25th of this month.
Thickly covered with fog, there was a total absence of sunlight
.A high pressure zone has settled over the region in the upper levels. By Thursday, the clock wise winds (high pressure in upper region) will turn anti clockwise (low in the upper air)

The cold days on 25th.

Kurukshetra 9.2c (Incidently, even Chamba was 9.2c in the day on 25th)
Karnal 9.5c (-12). the minimum was 8c.
Aligarh 10.8c (-10)
ambala 11c (-10),
Chandigarh 11.1c (-10)
Patiala 12c (-8)
Barelli 12c (-10)
Agra 13c (-10) minimum 4.6c
Palam 15.4c
Allahbad 15.5c(-9) minimum 4.9c
Gaya 13.9c (-10)

the lowest night temperature reached 1c at Narnaul.


Arpit Sharma said...

Purulia in Bihar is consistently recording below 15c from the past 10 days...

Arpit Sharma said...

Please read the above city as Purnea in Bihar...

Rajesh said...

First,very briefly, what type of fog has formed over the plains of N.India.
This fog, ground fog, is basically a cloud formed as a mass of moist air is trapped beneath a relatively warm air mass.It is nothing but stratus cloud.
A cloud, it is well known, prevents the loss of heat at night into space, and prevents the air temperatures from falling at night..similarly this cloud too, only it is at ground level.

Secondly, this cloud, fog, is 100%moisture, and the dew point is equal to the air temperature.
for the air temperature to fall, the dew point should differ, and fall further, which it cannot, as rhe moisture content is already 100%.
due to fog, the day remains very cool, but the night does not show much variation. it is the low day temperatures that make one feel the real it is in the day.
so, the night temperatures will never fall, and day/night difference will be low.
that is why I pointed out the difference between day and night temperatures for Karnal in the blog.
what was the difference ? Only 1.5c....unfortunately, I read all the answers in fb, and no one took this hint. !

Now, as we know, open spaces around the city are always cooler, due to less urbanisation.
n fact, I have noticed recently, Sjung remains cooler than Palam, a phenomena unheard of say 7years ago.
So, proportionately, the outer areas are cooler even in foggy conditions.

Rajesh said...

Mumbai dropping to 16.4c on 27th morning...and the short term cooling seen in Madhya Maharashtra. Punevat 7.4c

Rajesh said...

These day temperatures of 9c are amongst the lowest day temperatures on record for the plains stations. records are not easily available, but Delhi has seen 8c as the lowest day, and Amritsar has seen 8c too. There may be more ,but records have to be scanned.
I have Sialkot in Pakistan as having recorded 7c as day temperature .

Rajesh said...

On 21st of dec, a day night range difference of 28c , or 51F was recorded at Sibbi Pakistan...very stiff for a day !

emkay said...

seems there in a slight drop of post-noon temperature in Panvel

Rajesh said...

Max was 26.5 and min was -1.5c that day

Rajesh said...

Panvel unofficial was 13c today , Thursday

Viravanalluran said...

Usually the fog is classified into [1] radiation fog [2] Advection fog
Further fog is (stratus)cloud forming at ground level. Fog is a common affair during winter in upper latitudes.
When fog is thick and light rays can not penetrate it the insolation i.e in coming solar radiation is prevented and the earth is NOT getting heated. But losses energy out going long wave radiation relatively more. The pinge of cold will be felt in day time too.Here too the diurnal variation in temp will be less. [Max-min]
Similarly when the diurnal variation is large then also the cold bite will be felt. That will occur only in clear skies.

Abhijit Modak said...

Yes. Panvel 13 C quite possible as Badlapur was 11.8 C and IMD'S Karjat AWS recorded 11.6 C today. And even Puneet reported in Dombivli it was cold in morning. So Kalyan - Dombivli 14 C likely.

Abhijit Modak said...

And also Kolkata giving tough competition
to Delhi which is very far in North. As not
much difference in Kolkata & Delhi's max &
min temps from past few days.

Abhijit Modak said...

But I don't understand why Kolkata
very cold this year ! Breaking both min &
max temps records of over than decades !
What a chill there max just 18C & min 10 C.
Even in the absence of WD ! And also being
to near to Bay coast also ! And Dum Dum is just 8.6 C today.

Unknown said...

but being close to the arabian sea , mumbai also have seen low of 7.6 degree.

1st March: Mumbai: Parts of Mumbai received light drizzles on Thursday Night. Though rain was predicted in Interior Maharashtra, from an upp...