The following wind graphic, gives very sharp definition on strength and
direction. I'm assuming barometric pressure readings can only be obtained
via land, sea and air.? Instrumentation on satellites can show cloud and
heat patterns.

Is the following just clever computer graphics, combining the above
readings?

http://earth.nullschool.net/#current....33,44.51,1306

On 18/08/2015 17:52, Freddie wrote:
"Bertie Doe" Wrote in message:
The following wind graphic, gives very sharp definition on strength and
direction. I'm assuming barometric pressure readings can only be obtained
via land, sea and air.? Instrumentation on satellites can show cloud and
heat patterns.

Is the following just clever computer graphics, combining the above
readings?

http://earth.nullschool.net/#current....33,44.51,1306




Isn't it cloud movement vectors taken from a sequence of satellite
images, with a model wind vector field for background
data?


For atmospheric levels where there are suitable clouds, yes.

There are also satellite instruments (currently 'ASCAT' on Metop-A/B &
RapidScat on ISS) called scatterometers. These are basically radars
which measure surface winds over the ocean by the level of radar energy
backscattered from small (~20cm) wind-driven waves; the higher the wind,
the higher the waves, the higher the backscatter energy. By looking
45deg ahead, sideways & 45deg backwards as the satellite overpasses a
patch of ocean, the multi-view backscatter can be used to estimate both
wind speed & direction. There's also a passive microwave instrument
called WindSat which does a similar job via different polarisations. And
vertically-looking radar altimeters (e.g. Jason) can measure oceanic
wind speed (but not direction). So ocean surface winds are pretty well
globally covered.

For more details, see e.g.
http://www.eumetsat.int/website/home...CAT/index.html

Dave

"Dave Offiler" wrote in message ...

On 18/08/2015 17:52, Freddie wrote:
Isn't it cloud movement vectors taken from a sequence of satellite
images, with a model wind vector field for background
data?


For atmospheric levels where there are suitable clouds, yes.

There are also satellite instruments (currently 'ASCAT' on Metop-A/B &
RapidScat on ISS) called scatterometers. These are basically radars which
measure surface winds over the ocean by the level of radar energy
backscattered from small (~20cm) wind-driven waves; the higher the wind,
the higher the waves, the higher the backscatter energy. By looking 45deg
ahead, sideways & 45deg backwards as the satellite overpasses a patch of
ocean, the multi-view backscatter can be used to estimate both wind speed &
direction. There's also a passive microwave instrument called WindSat which
does a similar job via different polarisations. And vertically-looking
radar altimeters (e.g. Jason) can measure oceanic wind speed (but not
direction). So ocean surface winds are pretty well globally covered.

For more details, see e.g.
http://www.eumetsat.int/website/home...CAT/index.html

Thanks guys, that's really helpful and I've learned a new word
'scatterometers'. Thanks also for the link - now bookmarked.

"Bertie Doe" Wrote in message:
The following wind graphic, gives very sharp definition on strength and
direction. I'm assuming barometric pressure readings can only be obtained
via land, sea and air.? Instrumentation on satellites can show cloud and
heat patterns.

Is the following just clever computer graphics, combining the above
readings?

http://earth.nullschool.net/#current....33,44.51,1306




Isn't it cloud movement vectors taken from a sequence of satellite
images, with a model wind vector field for background
data?
--
Freddie
Pontesbury
Shropshire
102m AMSL
http://www.hosiene.co.uk/weather/
http://twitter.com/PontesburyWx for hourly reports


----Android NewsGroup Reader----
http://usenet.sinaapp.com/