Unit 1: Environment- Effects of Light and Heat on Ecosystems and Biomes

Light and Heat Effects on Ecosystems and Biomes

Transition from the ecosystem level to the biosphere level.
Focus on the effects of light and heat from the sun on ecosystems, biomes, and biome placement through climate.
Hybrid lecture format: combination of ecosystem and biosphere levels.

Long wavelength vs. short wavelength:
- Wavelength is the distance between successive peaks or valleys.
- Shorter wavelengths have more energy than longer wavelengths.
Speed of light is constant.
Photon energy:
- Short wavelength: Photon travels up and down more frequently, requiring more energy.
- Long wavelength: Photon travels up and down less frequently, requiring less energy.

Visible spectrum is the range of electromagnetic radiation that humans can see.
Different wavelengths trigger different sensors in our eyes, allowing us to see colors (red, yellow, green, etc.).
Combining all wavelengths of light results in white light.
Prism demonstration: Light separates into different wavelengths, showing a rainbow of colors.

Infrared (below red):
- Slightly less energy than red light.
- Not enough energy to trigger eye sensors.
- Adding energy would make it visible as red light.
Ultraviolet (above violet):
- More energy than violet light.
- Exceeds the threshold of what our eyes can detect.

Everything above absolute zero (0 degrees Kelvin) emits photons (thermal radiation).
These photons often do not have enough energy to trigger the sensors in our eyes.
Objects are visible due to reflected light rather than emitted photons.
Heated iron bar example:
- Initially, the bar is visible due to ambient light.
- Heating the bar increases the energy of emitted photons.
- Red light: Minimum threshold of photons our eyes are sensitive to.
- Yellow light: Higher temperature emits photons corresponding to yellow light.
- White light: High temperature emits photons covering all wavelengths simultaneously.
Sun's temperature emits visible light across the spectrum, resulting in white light, as well as infrared, radio waves, gamma rays, x-rays, and ultraviolet radiation.

Technology can receive and transform photons into visible pictures.
Infrared scopes/night vision: Capture photons emitted by objects and create an image.
Images are often displayed in shades of green.
Green filters are used in movies and TV to simulate night vision.
Black filters used in older movies to create the feeling of darkness; however, shadows reveal that filming wasn't actually at night.

Short wavelengths with high energy.
Can penetrate various objects.
Limited travel distance for accurate interpretation.
X-ray machine example: X-rays penetrate soft tissue and reflect off bones.
Person must be close to the machine for proper reading due to photon disintegration over distance.

Sunlight as a heat source striking the planet: influx and income versus expenditures.
The Earth's energy budget is generally balanced (heat in equals heat out).
The atmosphere complicates this balance.

Bottom layer of the atmosphere.
Where most weather occurs (rain, snow, sunshine, clouds).
Temperature decreases with altitude due to distance from molecules attracted to Earth by gravity.

Some weather impacts but not main weather systems.
Components:
- Jet stream: Fast-moving air affecting surface weather systems; influences airplane travel.
- Ozone layer: Absorbs sunlight energy, especially UV radiation; protects organisms from harmful radiation.

Ozone (O3) forms when oxygen gas (O2) molecules are broken apart into free oxygen atoms by sunlight.
Free oxygen atoms bind with oxygen molecules to form ozone.
Ozone layer in the stratosphere absorbs UV radiation.
Ozone depletion: Diminishes ozone layer, allowing more UVB radiation to strike the surface, causing skin and tissue problems in organisms.

Mesosphere: Separates the stratosphere from the thermosphere; relatively thin.
Thermosphere: Top layer of the atmosphere; very cold and very hot depending on sun exposure due to thinness of molecules.

Earth's Surface:
- Sunlight striking the earth: 51 units.
- Atmosphere radiating heat: 96 units.

Evaporation: 23 units (from open water, wet plants, wet soil).
Convection and Conduction: 7 units (movement of air molecules and physical touch).
Thermal Radiation: 117 units (photons liberating from the surface).

Solar radiation strikes Earth; some is reflected back from the atmosphere.
Some is absorbed by the atmosphere and clouds, eventually radiating into space.
Total heat coming in from the sun into Earth and its atmosphere equals heat radiated away into space.

Problem: Humans are altering the atmosphere by adding greenhouse gases (carbon dioxide, methane).
This causes the atmosphere to absorb and hold more heat, preventing it from radiating into space.
Altered convection and conduction: Surface loses less heat; may even gain some.
The equation is thrown off: 51 + 96 > 23 + 117

Natural warmth of Earth due to the atmosphere holding in heat.
Without the atmosphere, average temperature would be -18 degrees Celsius.
With the atmosphere, average temperature is around 18 degrees Celsius.
Climate change: Occurs when the atmosphere holds onto more heat due to human activities.
This affects ecosystems, communities, populations, and individuals.

Future lectures will cover climate formation relative to light and heat from the sun and Earth's movement around the sun.
Also, how biomes are placed around the globe because of light, heat, and climate.