Heating of the atmosphere

Heating of the Atmosphere

Introduction

  • The study focuses on how the atmosphere is heated and the mechanisms involved.

  • Key concepts and terminology related to atmospheric heating are reviewed.

Lesson Objectives

  • Understanding important terms related to atmospheric heating.

  • Identifying how heat is lost in the atmosphere.

  • Exploring methods of heat transfer within the atmosphere.

Important Terms

  • Albedo: The proportion of solar radiation reflected from a surface.

  • Electromagnetic spectrum: The range of radiation waves, from short to long wavelengths.

  • Heat budget: The balance of incoming and outgoing heat on Earth.

  • Insolation: Incoming solar radiation.

  • Terrestrial radiation: Long wave radiation emitted by the Earth.

  • Short wave radiation: Solar radiation received from the sun.

  • Long wave radiation: Heat re-radiated back to the atmosphere by the Earth.

Mechanisms of Heating

Insolation

  • Insolation refers to the energy from the sun that reaches the Earth.

  • Short wave radiation passes through the atmosphere and is absorbed by the ground.

  • The ground then radiates this heat back as long wave radiation, warming the atmosphere from below.

Greenhouse Effect

  • The atmosphere retains heat by trapping long wave radiation.

  • Greenhouse gases (e.g., carbon dioxide, methane, CFCs, water vapor) absorb and re-radiate heat back to the surface.

  • This process contributes to global warming and climate change.

Heat Loss in the Atmosphere

Key Mechanisms

  • Absorption

  • Scattering

  • Reflection

Mechanisms of Heat Loss

  1. Absorption

    • Most short wave radiation is absorbed by gases such as carbon dioxide and ozone before reaching Earth.

    • Clouds also absorb some incoming sunlight.

    • The Earth absorbs significant amounts of sunlight.

  2. Reflection

    • Reflection involves bouncing back of sunlight before absorption occurs.

    • A substantial amount is reflected by clouds, water, and land surfaces.

    • The amount reflected depends on surface type, measured as albedo.

    • Lighter surfaces (e.g., snow) reflect more heat than darker surfaces (e.g., forests).

  3. Scattering

    • Scattering occurs when air and dust particles send heat in every direction.

    • Responsible for the blue color of the sky, as sunlight is scattered.

    • On overcast days, clouds scatter all sunlight, resulting in diffused light.

Heat Transfer Methods from Earth to Atmosphere

Types of Heat Transfer

  • Radiation

  • Conduction

  • Convection

  • Evaporation

Explanations of Heat Transfer Mechanisms

  1. Conduction

    • Heat transfer when substances are in direct contact.

    • Energy moves from the hotter object to the cooler one until equal temperatures are reached.

    • Example: A metal spoon heats by conduction when placed in hot soup.

  2. Convection

    • Transfer of heat by vertical movement of air.

    • Warm air rises due to expansion and lower density, cools, and sinks back.

    • Example: Heating water in a kettle causes circulation as hot water rises and cold water descends.

  3. Evaporation

    • The conversion of liquid into gas absorbs heat, storing energy as latent heat.

    • When air rises and cools, condensation occurs, releasing stored latent heat.

    • Example: Opening a lid on a hot pot releases steam as vapor.

  4. Radiation

    • Transfer of heat via electromagnetic waves.

    • The Earth radiates long wave infrared heat, similar to how heaters work.

    • Example: Warmth felt when placing a hand near a heater.