Facts Flashcards
The angle between the plane of the ecliptic and the plane of the equator is approx?
23.5˚
At what approx date is the Earth furthest from the sun?
July
Aphelion
At what approx date is the earth closest to the sun?
4th January
Perihelion
Which of the following statement best describes mean sun?
A) The mean sun is a fictitious sun coinciding each year with the apparent sun at the Spring Equinox and travelling along the ecliptic at a uniform speed.
B) The mean sun is a fictitious sun coinciding each year with the apparent sun at the Spring Equinox and travelling along the celestial equator at a uniform speed.
B.
Think equator - uniform speed
as ecliptic orbit can be faster or slower depending on where on the foci the earth is from the sun.
When flying on a westerly great circle track in the Southern Hemisphere you will:
A) Fly a spiral track and finally end up at the South Pole
B) Experience a decrease in the value of the true track
C) Experience an increase in the value of the true track
A)
This is because the Q is asking for GC.
If the Q asked what the RL track did then it would spiral and finally end up at the pole.
What is “night”?
From the end of evening civil twilight (ECT) and the beginning of morning civil twilight (MCT).
The duration of civil twilight is the time?
Between sunset and when the centre of the sun is 6˚ below the celestial horizon
OR
Between sunrise and when the centre of the sun is 6˚ above the celestial horizon
On a Lambert’s conformal conic chart the convergence of the meridians
A) Equals convergency at the standard parallels
B) Varies as the secant of the latitude
C) Is the same as Earth Convergency at the Parallel of Origin
D) Is zero throughout the chart
C
How does chart convergency change with latitude on a lambert’s conformal conic chart?
A) it changes with the sine of latitude
B) it increases with an increase of latitude
C) it is constant and does not change with latitude
D) it changes with the cosine of latitude
C = is constant as does not change with latitude
This Q is asking about CHART convergency. As meridians are straight lines, the convergency is the same across the chart.
If the Q was about convergency in general then convergency will change with the sin of latitude.
Where on a direct Mercator chart is chart convergency correct compared with Earth convergency?
At the Equator
An aeronautical chart is conformal when:
At any point the scale over a short distance in the direction of the parallel is equal to the scale in the direction of the meridian and the meridians are perpendicular or the parallels.
How does the convergency of two meridians on the Earth change with varying latitudes?
A) It is a constant value and does not change with latitude
B) It changes with the cosine of latitude
C) It changes as sine of latitude
D) It increases with decrease of latitude
C = it changes as sine of latitude.
DO NOT get this confused with chart convergency.
This Q asks for Earth convergency, and of course this changes with sine of latitude as:
Convergency = chlong˚ x sin mean lat.
