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· At 2000 feet, wind is
unaffected by surface friction.
With no drift, you are parallel
to the isobars and true
altitude is constant.
· Your true altitude is
decreasing, because the 500-
foot wind is backed with
reference to the wind at 2000
feet, and you are crossing the
isobars from high to low
pressure because of the drift
you have to apply.
5. Wind speed will reduce by about
20%, so the coriolis effect will
automatically reduce by about 20°.
Thus, 360-20 is 340°, and 20% of 15
is 3, so the speed will be 12 kts.
6. At first sight, it would be 18, but
in late afternoon, the Coriolis effect
could well make it 21.
7. The airframe is cold, as you are
below freezing. You will therefore
most likely get clear ice.
8. Thin low stratus cloud.
9. It is valid between 2 in the
morning and 8 at night.
10. As the wind is light, and the
temperature is very close to the
dewpoint, you are very likely to see
radiation fog, because there is no
cloud and it is very near dawn. The
visibility is already poor, and will get
worse, before possibly clearing by
mid-morning after solar heating.
Note that the minimum RVR for a
visual approach is 1200m.
11. Valid between 6 in the morning
and 3 in the afternoon (UTC, of
course), the wind is from 150° at 30
kts, gusting 40, visibility 1200 metres
in mist. 3-4 oktas of cloud at 800'.
12. Temporarily between 1400 and
2000, 8000m visibility in showers
and rain. 30% probability of a
temporary reduction in vis to 5000m
between 1400 and 1500.
13. The temperature is 4°C and the
dewpoint 3°C, meaning that, if the
temperature falls, as it is likely to if it
is calm and clear, moisture will
condense out and form mist or fog.
Electricity & Radio
Radio depends on the movement of
electric and magnetic waves, which
depend on the movement of
electricity, which ultimately depends
on the activities of electrons inside
an atom.
Atomic Theory
Electrons are negatively charged
particles spinning rapidly round a
nucleus of positive- and neutrally
charged ones, called protons and
neutrons, respectively, as shown below
(the neutrons keep the protons
together, since particles of a like
charge are repelled):
None of them are physical in nature,
but are actually electromagnetic
charges, or tiny whirlwinds of
electromagnetic force. A collection
of atoms is called a molecule, which is
the smallest part of any object that
retains the identity of it.
Put very simply, if you line up a
series of atoms (as in an electrical
cable) and add an electron to the
first one, it will repel those already
there until one is pushed out, which
joins the next atom, and so on down
the line until an electron falls off the
last one, giving you an electric
current. When the electron is pushed
in at first, there is a difference in
potential between that end of the
cable and the other end, creating a
potential difference (another name for
voltage). In other words, the flow of
electricity is like that of wind moving
from high to low pressure.
Some atoms don’t have much of a
hold on their electrons, and allow
them to move easily – the materials
made up of these are called conductors
114 Canadian Private Pilot Studies
(copper is a good example – gold is
only used because it doesn’t tarnish
in a hurry, and cause bad
connections. A gas can also conduct
electricity). Those that keep a tight
hold and therefore allow no
movement are found in insulators,
which are used to keep conductors
from touching each other, otherwise
electricity would flow where you
don’t want it – if electricity takes a
short cut (known as a short circuit) it
generates massive amounts of heat,
with the obvious consequences.
Good examples of insulators would
be glass, or the plastic coating round
a cable.
Somewhere between a conductor
and an insulator is a semiconductor
which is created by adding a certain
amount of impurity to a material
normally considered to be an
insulator. Electricity will then flow
only under certain circumstances,
such as the influence of an
electromagnetic field, or the polarity
of the source of a current (this is the
basis of the transistor).
There must be an equal number of
electrons to protons, which is why
an extra electron (or a hole caused
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