# Which has the most intense sunlight hitting it?

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1. Feb 15, 2015

### shmijda

1. The problem statement, all variables and given/known data
Which has the most intense sunlight hitting it?

Question 2 options:
A point on the Equator at sunset

The North Pole at Noon on the Summer Solstace

Montreal at Noon on the Spring Equinox

The South Pole on the (Northern hemisphere) Summer Solstace

2. Relevant equations
none

3. The attempt at a solution
Ruled out first choice as it is at sunset.
Ruled out last choice as the South Pole does not receive much sunlight on the Summer Solstice
Stuck between choice 2 and 3.

2. Feb 15, 2015

### Bystander

What do you know about choices 2 & 3?

3. Feb 15, 2015

### Staff: Mentor

That's where you went wrong. Intensity can be described numerically, and then applying what you know about the Sun position in each case is a key to the correct answer.

4. Feb 15, 2015

### shmijda

We were supposed to do this without looking at the intensity numerically, so how do I choose between 2 and 3?

5. Feb 15, 2015

### Bystander

How far above the ecliptic plane are the two locations at the times of the year stated in the question?

6. Feb 15, 2015

### Staff: Mentor

You can't answer the question without comparing angles. Angles are numbers.

7. Feb 15, 2015

### vela

Staff Emeritus
You don't need to calculate the intensities, but you can reason mathematically which situation results in more intense sunlight. What determines how intense the sunlight is at noon?

8. Feb 15, 2015

### shmijda

The angle of incident rays? In this case I would say the north pole at noon

9. Feb 15, 2015

### Bystander

10. Feb 15, 2015

### vela

Staff Emeritus
Are you just guessing? What's the angle between the incident rays and the normal at the North Pole on the summer solstice? You should be able to figure this out knowing the tilt of the Earth and the fact that the North Pole is at 90 degrees latitude.

What about for Montreal on the vernal equinox? If your answer is right, the Sun should be lower in the sky than it was for the North Pole on the summer solstice. Can you justify that?

11. Feb 15, 2015

### shmijda

for north pole on summer solstice - I got angle 66.6
for montreal on equinox - angle 45.5

12. Feb 15, 2015

### vela

Staff Emeritus
Those look reasonable, so the Sun is lower in the sky in....

13. Feb 15, 2015

### shmijda

Montreal, thus North pole at noon on summer solstice is right?

14. Feb 15, 2015

### vela

Staff Emeritus
Those angles are between the incident ray and the normal. Zero degrees would correspond to the Sun being directly overhead, and 90 degrees would be if the Sun were on the horizon.