If asked which direction the sun rises, surely many people will answer easily: “The sun rises in the East and sets in the West” , but to determine which direction is East, which direction is West, it is not. everyone must know. There are many ways to determine the direction but determining the direction with the sun is the simplest method. You can find East, West, South, North directions easily.
From an early age, surely we all know a basic lesson about how to determine direction is:
In fact, this is not entirely correct. The position of the sun rising and setting in the year is not fixed but changes according to the cycle: Spring equinox, summer solstice, autumn equinox, winter solstice, and the sun only rises and sets in the East and West in the Spring and Autumn equinox. .
The direction of the sun can be determined. (Illustration).
Owen Doff was a British aviator who, throughout his life, traveled the world and found a way to navigate.
He tried more than 1000 times from all over, and gave approximate results with just a stick in the sun. To commemorate his merits, people called this method after him Oweb Doff.
Here’s how to do it:
Place the watch on a flat, horizontal ground and rotate the dial so that the short hand A (hour hand) coincides with the outer shadow of the tree. Draw the bisector OI of angle AOB (B is the number 12 and O is the clockwise axis).
Note: If it is the Southern Hemisphere, you will calculate the opposite.
The principle of this method is based on the phenomenon of the Sun rising and setting with respect to the Earth , forming a circle around the Earth, in 24 hours. The hour hand of a clock rotates once in 12 hours, that is, in the same time, the hand of the clock makes an arc more than 2 times larger.
In the opposite way, if we divide the North – South direction by two arcs drawn by the hour hand (with the position of the clock face as we did above), we will find the direction of the Sun appearing.
With this method not very accurate, the error can be up to tens of degrees. The main reason is that the clock face is placed parallel to the horizon plane, and the daily path of the Sun is only at the poles on the horizontal plane. At other latitudes, the line makes different angles to the horizon, which can be greater than 90 degrees (at the Equator). Therefore, only near the poles can this method be used to determine the direction for accurate results!
In addition to determining the direction according to the Sun, one also determines the direction according to the wind and other experiences.
Vietnam is located in the “Asian monsoon” region with two main wind types. Northeast Monsoon and Southwest Monsoon. The Northeast Monsoon operates from October this year to April next year, blowing from the Northeast to the Southwest. The southwest monsoon lasts from May to October every year, blowing from the southwest to the northeast.