Home' Afloat : AFLOAT October 2017 Contents Take monthly with water October 2017 61
by Malcolm Riley*
*Malcolm Riley worked for the Bureau of Meteorology for 34 years and
gives marine weather training to boating groups. He sails on tall ships
in various parts of the world and skippers the Lady Nelson in Hobart.
* Satellite Sollutions
* Marine Audio/Visual
* Marine Navigation
* Marine Communication
* Solar Systems
* Wind Systems
* LED Lighting
* IP/Thermal Cameras
HAWKES BOATYARD AIRLIE BEACH 07 4946 5203 TWENTY16.COM.AU
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Uranus, another gas giant (about 15 times the mass of Earth)
is cold. However, due to the temperature of the planet it is often
called an ice giant. The core of the planet is made of rock and ice.
The gasses of Uranus are similar to Saturn and Jupiter, mostly
hydrogen and helium. However, Uranus has much more ice in
the form of frozen ammonia and methane.
Uranus gets a much reduced energy feed than earth from
the sun due to its distance from the sun. Uranus gets about
1/400th of the light from the sun compared to the earth. So get
out your winter woollies, the average temperature as the Roberts
30 passes through the gasses of Uranus is around minus 300°C.
Uranus is also windy; winds can reach almost 500 knots (reef
early, reef often). Storms can generate on Uranus especially
during spring. Uranus axis of rotation is around 97° (Earth 23.5°).
Uranus is more or less lying on its side compared to earth.
Uranus rotates on its own axis around every 17 hours and orbits
the sun every 84 years. Seasons last for 21 years.
In the diagram below the northern hemisphere summer
(A) lasts 21 years with no light at all to the southern parts. The
southern summer (B) also lasts 21 years with no light getting
to northern parts. However during Spring (D) and Autumn (C)
the planet is side on to the sun and rotates every 17 hours or so.
This leads to huge imbalances in the heating of the atmosphere
and can generate pretty wild storms some about half the size
of Australia. Uranus is just about to enter 21 years of northern
It is thought that the reason for the much tilted axis of
rotation of Uranus was due to a series of collisions with large
objects (perhaps small planets) a sort of planetary snooker that
occurred in the early days of our solar system.
Cirrus-like clouds made of frozen methane particles blanket
Uranus. These clouds absorb red light but reflect the blue
light giving the planet
a blue colouring. You
may even get snow on
Uranus but it would be
made of frozen water,
Uranus has 27 moons
all up but only five major
Neptune is similar to Uranus and is another ice giant and
has some of the most extreme weather. Neptune’s atmosphere
is mostly made of hydrogen, helium and methane. The methane
gives the planet a blue colour, just like Uranus.
Astronomers have reported winds of over 1,000 knots. Storms
do develop on the planet but how they generate is still a mystery.
Neptune is also cold receiving only 1/1000th of the light from
the sun that we receive on earth. Neptune’s average temperature
is cold around minus 215°C; however, like the other gas giants, it
has a very warm core of around 5,000°C and it is heat from the
core that is thought to “drive” Neptune’s weather.
Neptune has 13 moons. One of them, Triton is about the
same size as the recently ‘delisted’ planet Pluto.
It is now time to turn our Roberts 30 around and head back
beating into the solar wind for home, never complaining about
earth’s weather again.
In researching for this article I have been amazed by the
exploration of space that has occurred. That the Russians landed
a craft on Venus in 1982; the Cassini and Juno space craft; Mars
rover; Hubble telescope and many many more are a tribute to
those that made these projects happen.
These space missions combine with all the other advances
that scientists and engineers have provided us (the human race)
in many fields here on earth. It is disappointing that governments
around the world seem to be not only reducing funding for research
but in many cases ignoring or even repudiating the science ...
climate change is a good example of this. h
In this fourth and final article of a series Malcolm
Riley* looks at some of the strange weather on other
planets. He is sailing a specially modified Roberts 30
through our solar system catching the solar wind to visit
other planets and looking at their weather.
Sailing a specially modified
Roberts 30 through our solar system
Storm on Neptune that
winds. This storm is roughly
the size of the earth.
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