How to measure the altitude angle of the sun?

This question is the same as when I was a senior in college, and my classmates measured the latitude and longitude.

First of all, the shortest time for the shadow of this pole is the local noon, and the length and direction of the shadow at this time are recorded.

Second, the length of the pole is divided by the length of the shadow, and then the arctangent is taken as the angle of the height of the sun at the time of measurement, which is a trigonometric function, and there is nothing to explain;

Third, the sun has been directly on the equator at the spring and autumn equinoxes, and the Tropic of Cancer and Tropic of Cancer at the summer and winter solstices. Then add or subtract from the angle obtained in the second step to get the local latitude value, whether it is addition or subtraction, depending on the measurement date, draw a diagram to understand;

Fourth, measuring longitude is actually measuring time. Beijing time is known to be the time of the 120th degree east longitude. Then record the time when the sun passes due south, that is, the shadow of the bamboo pole, and see the time difference between it and 12 o'clock Beijing time.

Every 4 minutes, the longitude is 1 degree worse, so that the longitude also comes out.

Stick the bamboo pole vertically into the ground, and measure the length of the bamboo pole L1 and the shadow length L2.

Then the local solar altitude angle is arctan (l1 l2) If you want to calculate latitude and longitude, you need the following two data:

1. The local time at this time (preferably noon).

2. Local dates.

If you want to calculate latitude and longitude, you need the following two data:

1. The local time at this time (preferably noon).

2. Local dates.

There are two ways to determine the solar altitude angle at noon:

Simple altimeter hyomin algorithm。Take a semicircular protractor and a plumb line, at noon, take the north-south direction, use sunglasses to the naked eye along the straight edge of the protractor and Tai Na Shen He Yang into a straight line, fix the protractor, at this time the plumb line and the straight edge of the protractor have an angle z, use the formula: h=90-z to find the sun altitude angle h.

Immediate results。Take a long bamboo pole and stand on the flat ground, from one hour before noon to one hour after noon, draw a point on the ground of Li Pai at the top of the rod shadow every 15 minutes or so, and finally connect all the points into a line to form an arc; Take the shortest distance between the bottom of the rod and the arc a, measure the length of the rod b, and the noon sun height angle h can be found by the following formula: the h value can be accurate to the minute.

Solar elevation angles in different regions.

Different. Take the Beijing area as an example, the latitude of the Beijing area is 40°N, and its solar altitude angles are:

1. Vernal equinox day: the sun directly hits the equator at 0°, and the solar altitude angle at noon in Beijing on that day = 90°-|40°-0°|=50°

2. Summer solstice.

The direct sun shines at 23°26 n, the height of the sun at noon in Beijing on that day.

Angle = 90°-|40°--23°26′|=73°26′

3. Autumn equinox day: the sun directly hits the equator at 0°, and the solar altitude angle at noon in Beijing on that day = 90°-|40°-0°|=50°

4. Winter solstice: the sun shines directly at 23°26 s, and the solar altitude angle at noon in Beijing on that day = 90°-|40°-（23°26′）|26°34′

Calculation formula: noon sun height = 90°-|Local geographic latitude - the point where the sun shines directly at this time.

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The law of the change of the height of the sun is only the angle of separation:

1. Latitude change law: the latitude and longitude where the direct sun point is located.

Decreasing to the north and south. It can be inferred that the latitude difference from the direct point of the sun is one degree, and the altitude angle of the sun at noon decreases by one degree. (It can be further concluded that the altitude angle of the sun at a certain noon is known, and there are generally two parallels equal to this degree).

For example, if the sun shines directly at 20°N, the elevation angle of the Sun at noon in the world will gradually decrease from 20°N to the north and south, and the solar elevation angle at noon at 19°N is equal to 89°.

That is, the height of the sun at noon at 19°n = 90° - (direct point of the sun - latitude of the place) = 90° - (20° - 19°) = 89°

2. The law of seasonal changes: the sun refers to the direct point of the jujube gradually increasing when it moves, and gradually decreasing when it moves (the direct point of the sun is relative to the latitude of a certain place).

For example, for a region of 31°N, the solar elevation angle increases at noon from December 22 (winter solstice) to June 22 (summer solstice), and decreases at noon from June 22 (summer solstice) to December 22 (winter solstice).

Use a ruler to measure the table.

The length of the nail on the model.

Place the model in the sun, turn the plank so that the shadow of the nail is cast on the board, and measure the length of the shadow of the nail.

Draw a straight angle ac on a triangle on the paper so that a= nail length and c = shadow length.

Connect the AC and use a protractor to measure the angle between the AC and the two lines, which is the height of the sun at the time of the laughing family's change.

The structure of the solar altitude measuring instrument consists of a metal protractor, a measuring frame, a vertical line hammer, a base, etc., and all parts are fixed on the base. 1. Park the instrument at the measurement location, adjust the horizontal screws on the base, so that the hammer line and the vertical on the dial completely coincide, and the instrument remains horizontal. Once adjusted, place the hammer wire behind the protractor.

2. Let the sun shine.

The line passes through the crosshair of the measuring frame and touches the gap and is projected onto the crosshair indicator on the opposite side, so that the projection and the cross on the indicator completely coincide. 3. Observe the degree on the dial pointed by the arrow of the measuring frame, that is, the sun altitude angle.

4. In case of cloudiness.

The weather is not clear about the projection, and the condenser lens can be changed to focus the sunlight on the reticle indicator for observation and comparison. 5. In this way, you can observe the solar altimeter at different times of the day, and you can also observe and record the changes in the height of the sun in a year.

The height of the sun at noon.

It can be measured by observing the shadow of the object.

If a 1-meter-long bamboo pole is inserted vertically into the ground, and the shadow length is x meters, the pole and the shadow form a right-angled triangle perpendicular to each other.

The end of the shadow and the fixed point of the bamboo pole are connected by the hypotenuse of a right triangle.

The angle between the shadow and the hypotenuse type is the angle of the sun at this time.

tan = pole length god guess shadow length.

The greater the sun altitude angle, the shorter the shadow of the bamboo pole.

Longitude calculation: at noon the sun height is the largest of the day, then the shadow is the shortest, measure the shadow length change in a few hours before and after noon, when the shadow is the shortest time is 12 noon in the local place, and record the Beijing time displayed by the watch at this time, Beijing time is the East Eighth District.

Zone time, that is, at 120° east longitude, according to the time difference between the local area and the time at 120° east longitude, (the difference in longitude is 15° and the time difference is 1 hour; 4 minutes for every 1° difference in longitude) calculates the difference in longitude between the local and 120° east longitude, and further determines the local longitude based on the fact that the east side of the earth is always earlier than the west time, i.e., the time passes faster.

Latitude calculation: When the shadow is the shortest, the height of the sun is the maximum of the day, and the local time is 12 o'clock local time, the sun at this time.

The high edge is the height of the sun at noon on the day, using the solar height formula:

Noon solar altitude = 90° - latitude interval (i.e., direct point and local latitude interval).

The local latitude can be calculated, and in order to know exactly the latitude of the direct point, you can choose the winter solstice (the sun shines directly at 23°26 south) or the summer solstice.

The sun is directly shining at 23°26 north latitude), or the spring or autumn equinox (when the sun is directly at the equator).

The following is for reference.

The height of the sun at noon can be measured by looking at the shadow of an object.

If a 1-meter-long bamboo pole is vertically inserted into the ground, and the shadow length is x meters at this time, then the pole and the shadow form two straight edges of a right-angled triangle perpendicular to each other, and the endpoint of the shadow and the fixed-point connection of the bamboo pole is the hypotenuse of the right-angled triangle, and the angle between the shadow and the hypotenuse is the sun height angle at this time

tan = rod length shadow length.

The greater the sun altitude angle, the shorter the shadow of the bamboo pole.

Longitude calculation: at noon the sun height is the largest of the day, the shadow is the shortest, measure the shadow length change in a few hours before and after noon, when the shadow is the shortest time is 12 o'clock at noon in the local place, and record the Beijing time displayed by the watch at this time, Beijing time is the time when the base is late in the East Eighth District, that is, when the place of 120 ° east longitude, according to the time difference between the local time and the local time of 120 ° east longitude, (the difference in longitude is 15 ° and the time difference is 1 hour; 4 minutes for every 1° difference in longitude) calculates the difference in longitude between the local and 120° east longitude, and further determines the local longitude based on the fact that the east side of the earth is always earlier than the west time, i.e., the time passes faster.

Latitude calculation: When the shadow is the shortest, the height of the sun is the maximum of the day, and this front time is 12 o'clock local time, when the sun is at this time.

The altitude is the height of the sun at noon on the day, using the solar height formula:

Noon solar altitude = 90°-latitude interval (i.e., the distance between the direct point of the section and the local latitude).

The local latitude can be calculated, and in order to accurately know the latitude of the direct point, you can choose the winter solstice (the sun directly reaches 23°26 south latitude) or the summer solstice (the sun directly reaches 23°26 north latitude), or the spring or autumn equinox (the sun directly reaches the equator).

Here's how to measure the solar altitude angle at noon:

Prepare the tools: You'll need a horizontal wooden or aluminum stick, a projector, a piece of white paper or other reflective surfaces, and a goniometer.

Choose a location: Choose a wide, flat field to avoid obstacles such as trees and buildings.

Prepare the sticks: Place the wooden or aluminum sticks on the ground so that they are perfectly level with the ground.

Projector: Fix the projector on a wooden stick so that it is parallel to the ground number loss plane.

White paper: Place white paper underneath the projector to collect the sun's shadows.

Measurement: At noon, observe the length of the sun's shadow on the white paper. Use a goniometer to measure the angle between the shadow and the ground, which is the angle of the sun's height.

Note: Avoid eyes that are exposed to direct sunlight when measuring, and use protective measures such as sunscreen goggles or a hat with a shade cloth.

The following is for reference, the height of the sun at noon can be measured by observing the shadow of the object, such as a 1 meter long bamboo pole vertically inserted into the ground, at this time the shadow length is x meters, then the pole and the shadow are perpendicular to each other to form two straight sides of a right triangle, the end point of the shadow and the fixed point connection of the bamboo pole is the hypotenuse of the right triangle, and the angle between the shadow and the hypotenuse is the sun height angle at this timetan = pole length The greater the shadow length of the sun height angle, the shorter the shadow of the bamboo pole. Longitude calculation:

At noon, the height of the sun is the largest of the day, then the shadow is the shortest, measure the shadow length change in a few hours before and after noon, when the shadow is the shortest time is 12 o'clock at noon in the local place, and record the Beijing time displayed by the watch at this time, the Beijing time is the time of the East Eight District, that is, the place of 120 ° east longitude, according to the time difference between the local area and the local time of 120 ° east longitude, (the difference in longitude is 15 ° and the time difference is 1 hour; 4 minutes for every 1° difference in longitude) calculates the difference in longitude between the local and 120° east longitude, and further determines the local longitude based on the fact that the east side of the earth is always earlier than the west time, i.e., the time passes faster. Latitude calculation: When the shadow is the shortest, the sun height is the maximum of the day, and the local time is 12 o'clock at this time, and the sun height at this time is the noon sun height of the day, using the solar height formula:

In order to accurately know the latitude of the direct point, you can choose the winter solstice (the sun directly reaches 23°26 south latitude) or the summer solstice (the sun directly reaches 23°26 north latitude), or the spring or autumn equinox (the sun directly reaches the equator) with the above method to measure and calculate.