What you’ll learn10 learning objectivesChoose one objective for a focused lesson, or study the complete topic.—B.2.1—Conservation of energy• Conservation of energy.Syllabus objective—B.2.2—Emissivity• Emissivity compares surface radiation per unit area with a black body: ε = power/(σT^4).Syllabus objective—B.2.3—Albedo• Albedo = total scattered power / total incident power.Syllabus objective—B.2.4—Earth’s albedo variation• Earth’s albedo varies daily with cloud formation and latitude.Syllabus objective—B.2.5—Solar constant S• Solar constant S.Syllabus objective—B.2.6—Mean solar intensity• Mean incoming solar intensity is S/4 due to planetary geometry.Syllabus objective—B.2.7—Greenhouse gases• Main greenhouse gases: CH4, H2O, CO2 and N2O from natural and human sources.• Greenhouse gases have both natural and human-created origins.Syllabus objective—B.2.8—Infrared absorption• Greenhouse gases absorb IR via molecular energy levels.• Radiation is re-emitted in all directions.Syllabus objective—B.2.9—Greenhouse models• Explain greenhouse effect using resonance and molecular energy-level models.Syllabus objective—B.2.10—Enhanced greenhouse effect• Enhanced greenhouse effect = augmentation due to human activity.Syllabus objective