Water Cycle and the Atmosphere

Where is water on Earth?

• Reservoirs- protected artificial or natural lakes

• Groundwater- water that collects underground

Water Cycle• The continuous movement of water from

the atmosphere to the earth’s surface and back to the atmosphere again. – Aka: hydrologic cycle

• Parts of the Water Cycle– Evaporation– Transpiration– Runoff– Ground Water– Condensation– Precipitation

• Parts of the Water Cycle– Evaporation: liquid water changes into water vapor– Transpiration: plants give off water vapor into the

atmosphere – Runoff: flows over land into rivers – Ground Water: water that soaks deep into the soil and

rock underground – Condensation: water vapor cools into tiny liquid water

droplets (clouds)– Precipitation : water falls from clouds to the earth’s

surface (rain, snow, sleet, and hail) – Aquifer: Underground area of sediment and rocks that

hold groundwater

What's in Earth's atmosphere?

• This protective layer exists around Earth because our planet has just the right balance of size and distance from the sun.

The Atmosphere

• Earth’s atmosphere is a layer of gases surrounding the planet, protecting and sustaining life.– It insulates us so that we

don’t freeze at night. – Its ozone layer protects us

from the sun’s ultraviolet rays.

Atmospheric pressure

• Atmospheric pressure is a measurement of the force of air molecules in the atmosphere at a given altitude.

• The pressure of the atmosphere changes as you rise above sea level.

Pressure changes with altitude

Parts of an Aneroid Barometer

Layers of the Atmosphere

• Four Layers

– Thermosphere– Mesosphere– Stratosphere– Troposphere*

• The atmosphere is divided into layers based on temperature changes.

• We live in the troposphere which is 0 to 11 kilometers above Earth's surface.

Layers of the Atmosphere

The four layers of the atmosphere include:

1. the troposphere, where we live;

2. the stratosphere, which contains the ozone layer;

3. the mesosphere, where meteors burn;

4. and the thermosphere, where satellites orbit Earth.

Energy in the Atmosphere

Our sun converts 5 million tons of its own mass into energy every second.

This process involves nuclear fusion.

Even though Earth intercepts only a tiny fraction of the radiation broadcast by the sun into space, this radiation provides most of Earth’s thermal energy.

Greenhouse effect There are molecules in the atmosphere that

act like the pebbles in the bucket. They make it take longer for the infrared

radiation to escape back into space compared to bucket with no pebbles.

Greenhouse effect

• Adding greenhouse gases to the atmosphere is like adding more pebbles to the bucket.

• It takes longer for radiation to escape from the atmosphere, so Earth’s average temperature rises.