Section One: 1. The Earth, 2. Aeronautical Charts Flashcards
What name is given to the point at which the Earth is closest to the Sun in its orbit?
Perihelion
What name is given to the point at which the Earth is furthest to the Sun in its orbit?
Aphelion
The Earth’s axial tilt means the sun’s position changes in what manner?
Latitudinally
In the Northern Hemisphere’s Summer solstice, where does the Sun appear directly overhead at noon?
Tropic of Cancer
In the Northern Hemisphere’s Winter solstice, where does the Sun appear directly overhead at noon?
Tropic of Capricorn
At the spring and autumn equinox, the Sun appears directly overhead where?
Equator
In reality, the Earth is what kind of shape?
A flattened spheroid
The Earth rotates around which axis?
Polar axis
For the purposes of practical navigation, the North Pole is the direction of…
True North
Basic reference for longitude
Greenwich Meridian
Greenwich Meridian is otherwise known as what?
Prime Meridian
The longitude of 180 degrees E/W is otherwise known as what?
Anti-meridian
Longitude is the angle between?
A location’s meridian of longitude and the Prime Meridian
The angle between a location’s meridian of longitude and the Prime Meridian is known as what?
Longitude
Slices of the Earth in longitude are given what term?
Meridian
Slices of the Earth in latitude are given what term?
Parallel
The North and South Poles are what degree of Latitude, respectively?
90 degrees
How is the degree of Latitude calculated?
Angle between the plane of the Equator and the line drawn to the parallel of Latitude at the Earth’s surface
What is a Great Circle?
A plane passing through the centre of the Earth when represented by a sphere
Meridians of longitude and the Equator can be described as what?
Great Circles
What are some navigational examples of Great Circles?
Meridians of Longitude and the Equator
The shortest distance between any two points on the Eath’s surface lie on what plane?
A Great Circle
Great Circles have two major properties:
Shortest distance between two points
There can only be one Great Circle (except between antipodal points)
Two locations that lie on exact opposite sides of the Earth are known as?
Antipodal points
Parallel of Latitudes can be described as what kinds of distances?
Small Circles
Example of Small Circles
Parallel of Latitudes
How is a specific plane through the Earth not a Small Circle?
It does not pass through the centre of the Earth
A spherical plane between two points that does not pass through the centre of the Earth is known as what?
Small Circle
What is the normal reference direction from which angles are measured?
True North
The distance between latitudes increases with what direction?
Heading towards the Equator (from either north or south)
What is the term given to the angle of inclination of two meridians at a latitude?
Convergence
Convergence = 0 where?
Equator
Why is there no longitudinal convergence at the Equator?
The meridians are parallel
Why is there full longitudinal convergence at the Poles?
The Poles are where the meridians ‘meet’
How is convergence calculated between two meridians at the poles?
The latitudinal angle between them at the Equator = convergence at the poles
What term is given to a line between two points that maintains a constant angle of direction relative to true north?
Rhumb line
3 instances when Great Circle line = Rhumb line
Flights along meridian of longitude
Flights along the Equator
Short distance flights
Why is the Great Circle of a flight along a meridian of longitude also its rhumb line?
All meridians are arcs of great circles
On a rhumb line flight, what will constantly change?
The track bearing
The Decimal Degree coordinate notation appends a negative ‘-‘ sign to which directions?
South and West
The Decimal Degree coordinate notation appends a negative ‘+’ sign to which directions?
North and East
1 nautical mile is equivalent to…
The angular distance of 1 minute of arc on the Earth’s surface
1 minute of latitude at any point on the Earth is equivalent to
1 nautical mile
Why does a nautical mile change in different locations?
The Earth is not a perfect sphere
How many feet in an international nm?
6076
How many metres in an international nm?
1852
1 degree of longitude is equal to what distance at the Equator?
60nm
1 degree of longitude is only equivalent to 60nm where?
Equator
What happens to the distance between degrees of longitude as you move further from the Equator?
The distance decreases (from 60nm)