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Wavy temperature profile. Why?


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 Observing the temperature of a level in the atmosphere, e.g 850 hPa of Madrid(Spain), we can identify a wavy pattern of it, with a specific periodic behaviour of it with a maximum after the noon and then a minimum early in the morning.

You have to ignore of course the general tendency of the temperature via many days where it is being affected by genera; circulation heat or cold surges, so we actually speak about local minimum and maximum over each day.

 Then looking at another place's temperature which is much southern than Madrid, so let's take Granada which is about 3° southern of Madrid, we see that this wavy pattern again, but its amplitude(its vertical spread -or if you like the difference of maximum from minimum) is smaller.

This can be seen much better with another 2 cities, this time of Greece, Athens and Thessaloniki, where in Thessaloniki the wavy pattern of temperature in 850 hPa is much more obvious than in Athens. I.e the difference of maximum temperature from minimum in every day is a lot bigger in Thessaloniki than in Athens and in Athens the wavy pattern is actually very weak.

 

So let's see all that via GFS's diagrams for the current period:

 

Madrid:

image_485_zps47f7b73e.gif

 

Granada:

image_486_zps20e0c736.gif

 

Athens:

image_487_zpsae36d2d6.gif

 

Thessaloniki:

image_488_zpsc95d6f5a.gif

 

 

◙◙◙ Now my question is:

a)WHY this is happening? Why there is this wavy pattern in the temperature profiles in 850 hPa?

b)Also why as we go southern this wavy pattern is weakening? And so why in Athens it becomes so small?

 

 An obvious try to explain a), is that the height where 850 hPa is, is inside PBL so it is heated by the earth's surface, which is heated by the sun, so it reaches its maximum temperature a little after the sun's maximum height in the sky every day, and that is a little after the noon. Similarly at night where the sun is below horizon its temperature will normally fall and we would get a minimum around the time, or a bit after it, where the sun will appear again above the horizon.

But is this really the correct and full explanation for the wavy pattern?

 

And anyway, the above doesn't explain cool.png.

 

Furthermore if we look at the temperature profile of various heights(for Madrid-it's the same for other places also):

39766013_metgram_zps39222f52.gif

 

We can see that this wavy pattern(with local maximum/minimum for each day) is valid for all atmospheric levels up to 800 hPa approximately.

c)So does that mean that my previous explanation of the PBL is correct and that 850 hPa, 830 hPa, 800 hPa, etc, are being heated by the earth's surface so that's why we have this wavy pattern? Or something else is true?

d)So in what height is the PBL aproximately in these diagrams? I thought it is lower than 850 hPa but i guess i'm wrong, right?fool.gif

The important question cool.png remains though.sorry.gif

 

 

BTW this obvious wavy pattern starts to appear in these countries in late April most of the times, so that strengthens my aforementioned explanation for a), as then the sun is getting to affect in a greater degree the lower atmosphere in the north hemisphere.

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  • Location: Mostly Watford but 3 months of the year at Capestang 34310, France
  • Weather Preferences: Continental type climate with lots of sunshine with occasional storm
  • Location: Mostly Watford but 3 months of the year at Capestang 34310, France

    I suspect it has something to do with the proximity of the sea, but not just that but its temperature as well, together with the question of whether the wind originates from the land or sea which has the effect of evening out diurnal patterns of temperature, as in the case of Athens whereas Madrid which is pretty well inland has more marked differences.

     

    I note also the differences become smaller with height.

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