[LINK] Depiction of wind at various altitudes, other weather pages

Robin Whittle rw at firstpr.com.au
Thu Dec 19 12:42:32 AEDT 2013


Here is a new addition to my collection of weather URLs:

  http://earth.nullschool.net/

I read about it at http://www.universetoday.com.  It is a
javascript-driven, apparently very fluid, display of wind direction
anywhere on Earth, with data updated from various models every 3 hours.
 There is also the ability to look back in time and to look forwards by
up to 24 hours.

The "earth" thingo at the bottom opens up a menu from which various
settings can be selected, with the "about" link providing an
explanation.  Settings can be stored in a URL:


http://earth.nullschool.net/#current/wind/isobaric/1000hPa/orthographic=-225.44,-36.35,416

It is evident that the jetstream at about 10km (250hPa) is very
different from winds at the surface.  I don't understand how the
jetstream makes sense in terms of what I understand about Hadley cells:

  https://en.wikipedia.org/wiki/Hadley_cell

On a day like today in Melbourne, at the western edge of a high pressure
system, I understand a significant amount of the heat we feel (predicted
maximum 40C) is due to hotter than normal, very dry, air piling up in
the troposphere after being transported there from the tropics.  This is
in addition to air arriving from the inland north.  This somehow
displaces air on the ground with dryer, hotter, air.  If that's the
case, I am not sure how it works with the jetstream winds doing
something apparently unrelated (to my eyes) with the anticlockwise winds
at ground level which result from the high pressure system.

My other weather links are:

  http://www.bom.gov.au/australia/charts/synoptic_bw.shtml
  http://www.bom.gov.au/vic/forecasts/melbourne.shtml
  http://www.bom.gov.au/vic/observations/melbourne.shtml

http://www.bom.gov.au/products/IDR023.loop.shtml?looping=1&reloaded=0&topography=true&locations=true&range=true#skip
  http://www.bom.gov.au/australia/satellite/
  http://www.bom.gov.au/jsp/watl/weather/obs.jsp?graph=all_obs&station=86068

The last one is for the nearby Viewbank weather station.  This shows the
last few days of temperature and other measurements, including the dew
point.  The dew point is a measure of the moisture content of the air.
When this drops suddenly, as it did a few hours ago, I understand (from
an explanation by a meteorologist) this is the dry Hadley cycle air
descending to ground level and somehow (I have no idea how) displacing
the more moist air which was previously at ground level.

A final link, which is only for the Melbourne area is:

  http://www.baywx.com.au/melbtemp.html

This page, one of several, shows the predicted minimum and maximum
temperatures with the observations filled in as the day progresses.
There's an archive of the graphs, which enabled me to generate
temperature graphs of the heatwave associated with the 2009 bushfires:

  https://en.wikipedia.org/wiki/Black_Saturday_bushfires

  https://commons.wikimedia.org/wiki/File:Melbourne-temp-2009-02-10.png

https://commons.wikimedia.org/wiki/File:Melbourne-temp-2009-02-10-compact.png


I understand those dramatic peaks in temperature are driven largely by
Hadley cells.

 - Robin








More information about the Link mailing list