Energy Transfer and Electromagnetic Radiation

A collection of flashcards covering key concepts related to energy transfer methods, electromagnetic radiation, and their relationships in the Earth's atmosphere.

Methods of energy transfer

Conduction, convection, and radiation.

Conduction

Heat transfers through direct molecular contact; works best in solids.

Convection

Heat transfers by movement of fluids; warm rises and cool sinks.

Radiation

Heat transfers through electromagnetic waves; can travel through space.

Most important energy transfer in the atmosphere

Convection.

Energy transfer from the Sun to Earth

Radiation.

Wavelength significance in EM radiation

It determines energy level and how radiation interacts with matter.

Sun's emitted EM wavelengths

Short wavelengths: UV, visible light, near infrared (0.2–2.0 µm).

Earth's emitted EM wavelengths

Long wavelengths: thermal infrared (4–25 µm).

Effect of substance absorbing EM radiation

Converts radiation into heat; temperature increases.

Effect of substance transmitting EM radiation

Radiation passes through without heating the material.

Effect of substance redirecting EM radiation

Radiation is reflected or scattered away with no heating.

Albedo

The percentage of incoming solar radiation that is reflected.

Albedo and solar radiation relation

High albedo reflects more sunlight; low albedo absorbs more.

Selective absorber

A material that absorbs some wavelengths but transmits others.

Selective absorbers and the Greenhouse Effect

Greenhouse gases absorb Earth’s infrared but let sunlight pass, trapping heat.

Selective absorbers and the ozone layer

Ozone selectively absorbs UV radiation, protecting life.

How the Greenhouse Effect works

Sunlight warms the surface → Earth emits IR → greenhouse gases absorb it → atmosphere warms.

Important greenhouse gases

Water vapor (H₂O), carbon dioxide (CO₂), methane (CH₄).

Earth's shape and temperature differences

Curved surface causes direct sunlight at the Equator and low-angle sunlight at the poles.

Hydrologic cycle

Besides moving water, it also moves energy (latent heat).

Methods of energy transfer

Conduction, convection, and radiation.

Conduction

Heat transfers through direct molecular contact; works best in solids.

Convection

Heat transfers by movement of fluids; warm rises and cool sinks.

Radiation

Heat transfers through electromagnetic waves; can travel through space.

Most important energy transfer in the atmosphere

Convection.

Energy transfer from the Sun to Earth

Radiation.

Wavelength significance in EM radiation

It determines energy level and how radiation interacts with matter.

Sun's emitted EM wavelengths

Short wavelengths: UV, visible light, near infrared (0.2–2.0 µm).

Earth's emitted EM wavelengths

Long wavelengths: thermal infrared (4–25 µm).

Effect of substance absorbing EM radiation

Converts radiation into heat; temperature increases.

Effect of substance transmitting EM radiation

Radiation passes through without heating the material.

Effect of substance redirecting EM radiation

Radiation is reflected or scattered away with no heating.

Albedo

The percentage of incoming solar radiation that is reflected.

Albedo and solar radiation relation

High albedo reflects more sunlight; low albedo absorbs more.

Selective absorber

A material that absorbs some wavelengths but transmits others.

Selective absorbers and the Greenhouse Effect

Greenhouse gases absorb Earth’s infrared but let sunlight pass, trapping heat.

Selective absorbers and the ozone layer

Ozone selectively absorbs UV radiation, protecting life.

How the Greenhouse Effect works

Sunlight warms the surface
ightarrow Earth emits IR
ightarrow greenhouse gases absorb it
ightarrow atmosphere warms.

Important greenhouse gases

Water vapor (H2O), carbon dioxide (CO2), methane (CH4).

Earth's shape and temperature differences

Curved surface causes direct sunlight at the Equator and low-angle sunlight at the poles.

Hydrologic cycle

Besides moving water, it also moves energy (latent heat).

What happens to solar radiation that reaches Earth’s surface?

About 50% is absorbed, heating the land and oceans.

What percentage of incoming solar radiation is redirected back into space?

About 30%.

What term describes the amount of solar radiation reaching Earth’s surface?

Insolation.

Why doesn’t the atmosphere absorb much visible solar radiation?

Atmospheric gases do not efficiently absorb short-wavelength visible light.

What type of radiation does the atmosphere absorb well?

Long-wavelength infrared radiation emitted by Earth.

Why is Earth’s surface warmer than it would be without an atmosphere?

Greenhouse gases trap infrared radiation and warm the lower atmosphere.

Why is conduction the least important heat transfer method in the atmosphere?

Air is a poor conductor of heat.

Why is convection important in weather formation?

Rising warm air and sinking cold air create atmospheric circulation.

What is latent heat?

Heat absorbed or released during a change of state (solid, liquid, gas).

Which phase change absorbs energy from the environment?

Evaporation.

Which phase change releases energy to the environment?

Condensation.

Why does air near Earth’s surface tend to be warmer?

The surface absorbs solar radiation and heats the air from below.

What causes atmospheric and oceanic convection currents?

The imbalance in heating between the Equator and the poles.

What happens to energy when water evaporates?

It is absorbed and stored as latent heat.

What happens to energy when water vapor condenses?

It is released back into the atmosphere as heat.

Why does sunlight have to pass through more atmosphere at the poles?

The curved shape of Earth causes low-angle solar radiation.

Why do darker surfaces heat up faster than lighter surfaces?

Dark surfaces have low albedo and absorb more radiation.

Why do lighter surfaces stay cooler?

They have high albedo and reflect more solar radiation.

Why can radiation travel through space but conduction and convection cannot?

Radiation does not require a medium; it travels as electromagnetic waves.