Summary of "Radiación Solar y Radiación Terrestre - Meteorología"

Radiation basics

Radiation is energy transmitted by electromagnetic waves. It does not require a medium and travels at the speed of light.
All bodies emit electromagnetic radiation. The amount and the peak wavelength emitted depend mainly on temperature.

The Sun’s photosphere temperature is roughly 6,000 K, producing a broad emission spectrum that peaks in the visible range.
Approximate breakdown of solar emission by band (from the subtitles):
- Visible: ~42%
- Infrared: ~49%
- Ultraviolet: ~8%
- X‑rays / gamma / microwaves: ~1%
Solar constant (average solar power at the top of the atmosphere): ≈ 1,367 W/m².

Before reaching the surface, incoming solar radiation is partly reflected and partly absorbed by the atmosphere and clouds; the remainder reaches the surface.
Averaged planetary fractions given in the subtitles (approximate):
- ≈ 19% absorbed by the atmosphere and clouds.
- Planetary albedo (reflected to space) ≈ 30%.
- ≈ 51% reaches and is absorbed by the surface (average).
- Of the radiation that reaches the surface, a small portion (subtitle figure ≈ 4%) is reflected by the surface back to space; the rest is absorbed.
These percentages are global averages and vary strongly with cloud cover, surface type, latitude, season and time of day.

Albedo = percentage of incident radiation that a surface reflects.

Formula: Albedo = (reflected radiation / incident radiation) × 100%
Example: If a surface receives 80 W/m² and reflects 40 W/m² → albedo = (40 / 80) × 100% = 50%.
Typical surface albedos (from the subtitles):
- Snow: very high, ~80–95%
- Asphalt: low, ~5–10%
- Clothing example: white shirt ~80% (reflects most visible light → stays cooler); black shirt ~10% (absorbs most → gets hotter)
Note: An object’s perceived color depends on which visible wavelengths it reflects. Reflecting most visible wavelengths appears white; reflecting few appears black.

The warmed Earth emits longwave (infrared) radiation at longer wavelengths than the Sun because Earth is much cooler.
Greenhouse gases (CO2, CH4, water vapor, etc.) absorb much of this outgoing longwave radiation and re‑emit it in all directions. Some of this re‑emitted energy returns to the surface and warms it — the greenhouse effect.
The greenhouse effect is natural and necessary: without it Earth’s average temperature would be about −18 °C; with it the average near‑surface temperature is roughly +15 °C.

Surface:
- Absorbs ≈ 51% of incoming solar (average).
- Of that absorbed surface energy, ≈ 21% is emitted as longwave terrestrial radiation:
  - ≈ 15% of that longwave is absorbed by greenhouse gases.
  - ≈ 6% escapes directly to space.
- The remaining ≈ 30% of the surface energy is transferred to the atmosphere via conduction, convection, latent heat (evaporation/condensation) and sensible heat.
Atmosphere & clouds: previously absorbed ≈ 19% of incoming solar (subtitle figure).
Combined result: most outgoing longwave radiation is produced by the atmosphere/clouds plus surface emissions and transfers. The video states ~64% emitted as longwave to space and frames the system such that 100% incoming = 100% outgoing on a global average.
Important caveat: the transcript/subtitles contain some inconsistent or garbled numeric lines. Treat the exact percentage breakdowns as approximate, averaged values rather than precise constants.

Globally and in the long‑term average, incoming solar and outgoing terrestrial radiation are in rough balance, which helps explain relatively stable global temperatures over years.
The partitioning of absorbed vs. reflected energy varies regionally and temporally, driving climate and weather differences.
Albedo and greenhouse gas concentrations are key controls on how much solar energy is absorbed versus returned to space, and therefore on surface temperature.

The subtitles include a few transcription errors and inconsistent numeric phrasing (e.g., a line reading “approximately 26 percent 19 percent is reflected…”).
The summary retains the main repeated values (planetary albedo ≈ 30%, surface absorption ≈ 51%, solar constant ≈ 1,367 W/m²) and flags that detailed percentages are averaged and condition‑dependent.