What is the Sun's energy content at the Earth's equator?

  • Thread starter Thread starter royp
  • Start date Start date
  • Tags Tags
    Energy Equator
Click For Summary

Discussion Overview

The discussion focuses on the energy content of sunlight incident on the Earth's equatorial region during summer months, specifically seeking information on direct energy measurements rather than electrical outputs from solar panels. Participants explore the concept of solar insolation and its variations throughout the year.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant seeks to determine the direct energy content of sunlight at the equator, preferring measurements in KWh/square meter.
  • Another participant notes that solar insolation at the equator peaks at the equinoxes, not during summer, and mentions that insolation is measured in kW/square meter, requiring integration over time for energy density.
  • A participant comments on the fluctuation of the solar constant, which varies by about 6.9% throughout the year due to the Earth's distance from the Sun.
  • Some participants express confusion over the term "solar constant," discussing its implications and the variability it entails.
  • There is acknowledgment of the terminology used in describing the solar constant and its potential for misunderstanding.

Areas of Agreement / Disagreement

Participants express differing views on the implications of the term "solar constant" and its variability, indicating some disagreement on the terminology and its interpretation. The discussion remains unresolved regarding the best way to describe solar energy content and its variations.

Contextual Notes

Participants highlight the need for clarity in definitions and the impact of Earth's orbital characteristics on solar measurements. There is mention of the need to integrate power density over time to obtain energy density, which remains a point of discussion.

royp
Messages
55
Reaction score
22
TL;DR
What is the energy content of the sun rays falling on the equator in summer months
Hello,

I am looking to find out the energy (or power) content of the sunlight incident on the equatorial region during summer months. I assume, this is highest in that region. I actually want the direct energy content - not, say, the electrical output from a solar panel. This could be, in some way, a measure of heat. This may be available as KWh/square meter which will be most preferable.

Many thanks in advance for your help.
 
Engineering news on Phys.org
royp said:
I am looking to find out the energy (or power) content of the sunlight incident on the equatorial region during summer months. I assume, this is highest in that region. I actually want the direct energy content - not, say, the electrical output from a solar panel. This could be, in some way, a measure of heat. This may be available as KWh/square meter which will be most preferable.

Note that the solar insolation at the equator actually peaks at the equinoxes (when the sun is directly overhead) and is lower in summer and winter. Also, note that the insolation is a power density in kW/square meter, and would need to be integrated over some time period to give an energy density. At the Earth's surface it is about 1kW/m^2, as described in the article @Borek posted.
 
Borek, phyzguy : Many thanks! This will serve my purpose very well.
 
Borek said:

At first I thought this was some kind of scientific version of "mansplaining"

The actual direct solar irradiance at the top of the atmosphere fluctuates by about 6.9% during a year (from 1.412 kW/m² in early January to 1.321 kW/m² in early July) due to the Earth's varying distance from the Sun...

How on Earth can a constant vary?
But then I saw:

The solar constant is an average of a varying value.

Ok then.
 
Yes, the name is a bit of a misnomer.
 
  • Like
Likes   Reactions: OmCheeto
Borek said:
Yes, the name is a bit of a misnomer.

Were I a bit more ambitious, I'd go back through all 12 years of my PF posts, and put in a "± 6.9%" for all my solar experiments.
But, I'm not in the slightest bit ambitious, so, never mind.
 
OmCheeto said:
How on Earth can a constant vary?
You are right to question some sloppy terminology.
Bear in mind that the Earth's orbit round the Sun is not an exact circle. That means, despite any tilt or atmospheric factors, it can't be a 'constant'. It's a bad idea to get too hung up on 'words' when experimental evidence challenges them.
 

Similar threads

Replies
15
Views
2K
  • · Replies 1 ·
Replies
1
Views
3K
Replies
38
Views
9K
Replies
2
Views
1K
Replies
35
Views
8K
  • · Replies 24 ·
Replies
24
Views
4K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 19 ·
Replies
19
Views
9K
  • · Replies 67 ·
3
Replies
67
Views
7K