Question

shortly explain the foundation for global climates in terms of electromagnetic radiation from the sun and greenhouse effect

Answer 1

- The Sun supplies energy as electromagnetic radiation, mostly shortwave (visible and near-IR) with a solar constant ≈ 1361 W/m² at Earth; averaged over the planet this is ≈ 340 W/m².
- Much of that shortwave passes through the atmosphere and is absorbed by the surface and clouds; some is reflected back to space (planetary albedo ≈ 0.3).
- The warmed surface emits longwave (thermal infrared) radiation upward. The atmosphere is largely transparent to incoming shortwave but absorbs and re‑emits this outgoing longwave because of greenhouse gases (water vapor, CO2, methane, etc.).
- Absorption and re‑emission of infrared by the atmosphere keeps the surface warmer than it would be if Earth simply radiated directly to space — about 33°C warmer on average (surface ≈ +15°C versus effective radiating temperature ≈ −18°C). This is the greenhouse effect.
- The spatial and temporal pattern of incoming solar radiation (latitude, Earth’s axial tilt and seasons) plus redistribution of heat by the atmosphere and oceans produce the major climate zones and weather patterns.
- Changes in greenhouse gas concentrations and feedbacks (e.g., water‑vapor amplification, ice‑albedo changes, cloud responses) shift the balance between incoming and outgoing radiation, driving global climate change.

In short: solar shortwave warms Earth; greenhouse gases trap outgoing longwave, raising surface temperature; the balance and distribution of these fluxes set Earth’s global climate.