Method of measuring sun shadow with standard meter

The following methods are used to measure the sun shadow with a standard meter:

1, ready:

Choose a sunny day, make sure there is no shelter to prevent the sun from shining directly on the ground. Choose the flat ground as the measuring point.

2, set the standard table:

Place the instrument on a level ground to ensure that it is stable and vertical.

3. Adjust the standard table:

Use the adjusting device on the gauge to make the vertical rod of the gauge vertical to the ground and ensure that the base of the gauge is horizontal.

4. Observe the position of the sun:

During the measurement, observe the position of the sun. You can use the daylight indicator on a standard or other tool to help determine the position of sunlight.

5, observe the shadow:

When the sun shines directly on the ground, observe the sun shadow on the watch. The sun shadow is the shadow projected by the instrument on the ground.

6, measure the length of the shadow:

Use a measuring tool (such as a ruler) to measure the length of the sun shadow. Make sure to measure the length of the shadow, not the length of the standard itself.

7. Record data:

Record the measured shadow length.

8. Calculate the solar altitude angle:

According to the measured sun shadow length and the parameters of the standard table, the height angle of the sun can be calculated by trigonometric function and other methods.

Expand:

Ghost table is an astronomical instrument for measuring the length of the sun shadow, which consists of two parts: ghost table and ghost table. Like the sundial, the sundial is an ancient astronomical instrument, which uses the shadow of the sun to measure. The so-called altimeter method, popularly speaking, is to erect a pole perpendicular to the ground and determine the seasonal change by observing and recording the change of its shadow at noon. A straight rod perpendicular to the ground is called a "table", and a scale horizontally placed on the ground and engraved with scales to measure the shadow length is called a "GUI".

As early as the 20th century BC, during the period of Taosi ruins, the standard table drawing method was used in the Central Plains of China. Scholars in the Han Dynasty also determined the "twenty-four solar terms" by using the length of the sun shadow in the standard table, determined the shortest day in the Yellow River basin as the winter solstice, took the winter solstice as the starting point of the "twenty-four solar terms", and divided the period from winter solstice to the next winter solstice into 24 segments (each segment is 15 days), and the number of days between each two solar terms was averaged.