The Atmosphere, The Water Cycle & Ocean Currents

Where is most of Earth’s water found?

The Ocean

Where is most of Earth’s freshwater found?

Glaciers and ice caps

Glaciers

Land covered with ice that makes up much of the earth’s fresh water

Groundwater

Water held underground in layers of rock & sediment

surface water (Lakes, rivers, and ponds)

When the earth’s surface dips below the groundwater level

Aquifers

A layer of rock & sediment that can holds usable groundwater.

The Water Cycle

The continuous movement of water within the Earth and atmosphere. It is driven by energy from the sun and the force of gravity

Evaporation

The transfer of water from the earth’s surface to the atmosphere 

Liquid state → gaseous state

Transpiration

The evaporation of water from plants through small pores (stomata) on the leaves/stems of plants/trees

Condensation

Occurs when the air cools and cannot hold anymore water vapor. The water will be released in the form of precipitation.

gaseous state → liquid state

Precipitation

Water released from clouds in the form of rain, freezing rain, sleet, snow, or hail

Infiltration

Water soaks into the Earth’s surface moving into the pores and cracks of rocks.

Surface runoff

Water from precipitation that flows over the ground’s surface. This occurs when the ground is already too saturated for excess storm water, snow melt or impervious surfaces

Impervious surface

a hard, constructed surface that does not allow water to seep into the ground

Groundwater/Subsurface Flow

The movement of water underneath the Earth’s surface. This typically happens after precipitation has infiltrated the soil.

Accumulation (collection)

The process of water collecting in Earth’s oceans, rivers, lakes, and other bodies of water.

What are ways humans alter and affect the Water Cycle?

• Redirect rivers

• Build dams to store water

• Drain water from wetlands for development

• We use water for infrastructure and agriculture

• pollution

• climate change

Ocean current

the continuous,  predictable, and directional movement of seawater

Salt vs Fresh water

The salt water is more dense because of the added salt (adds mass without really changing the volume). As a result the salt water sinks

Warm vs. Cold water

Warm water is less dense because the molecules are moving faster and spread out more so the warm water rises/floats

Ocean Conveyor Belt

A constantly moving system of deep-ocean circulation driven by temperature and salinity. The great ocean conveyor moves water around the globe.

How does the Ocean Conveyor Belt form?

1. Water at the poles cools and freezes

2. Sea ice forms

   1. But the salt is left behind

3. Water that does not form ice is left saltier and colder than before

   1. This water is more dense and sinks

   2. Warmer water rushes in to fill its place

   3. Current has formed

What makes up air?

78% Nitrogen, 21% Oxygen, 1% Other. Solids, liquids, and gases…but mostly gases!

Air density

the amount of air molecules in a given area

Low density → low pressure → high temp.

High density → high pressure → low temp.

Air pressure

the amount of force exerted by air molecules. It is caused by gravity acting on the molecules.

Fewer molecules will exert less pressure
More molecules will exert more pressure

Wind

Wind is air flowing from high to low pressure.
It is air in motion

How do hot air balloons work?

When air is warmed, the molecules in it will move apart and the air becomes less dense. Air pressure also decreases because fewer molecules are in the same place.

How does wind form?

Wind is caused by the unequal heating of the Earth’s surface. Because Earth is curved, the sun’s rays strike the equator more directly than the poles.

Why is the atmosphere important?

• Protects organisms from the sun’s harmful rays

• Without the atmosphere, days would be extremely hot and nights would be extremely cold 

• Winds transport clouds, precipitation, and particles (like seeds) across the Earth

Troposphere

• Closest to the Earth’s surface

• contains 75% of the atmosphere’s mass

• weather, clouds, mountain tops

Troposphere distance

• thinnest layer

• 0-20 km

Troposphere temperature trends

• Warmed by the Earth’s surface

• As the altitude increases, the temp decreases

Stratosphere

• 2nd layer

• Contains the ozone layer

  • protects Earth from UV rays

• less dense than the troposphere

• Because the Ozone absorbs the UV rays, the temperature increases as the altitude increases

• Planes fly at the bottom of the Stratosphere

Stratosphere distance

20-50 km

Stratosphere temperature trends

Because the Ozone absorbs the UV rays, the temperature increases as the altitude increases

Mesosphere

• 3rd layer

• This layer does not absorb energy from the sun

• meteoroids burn up because of lots of friction

Mesosphere Distance

50-85 km

Mesosphere temperature trends

• the coldest layer

• the temperature decreases as the altitude increases

Thermosphere

• 4th layer

• Solar radiation hits here first! The few particles get tons of energy

• The International Space Station

• Aurora Borealis

Thermosphere distance

85-600 km

Thermosphere temperature trends

• hottest layer (over 1,000° C)

• feels cold because there isn’t enough matter to transfer the heat

• the temperature increases as the altitude increases

Exosphere

• 5th and outermost layer which gradually fades out to space

• satellites orbits and spaceships travel here

Exosphere Distance

600-10,000 km

Exosphere temperature trend

the temperature changes drastically