EXAM 1: Water/ Hydrologic Cycle

What does solar energy do?

powers life on earth and drive the hydrologic cycle.

What does it mean when saying the earth is in "Goldilocks Zone"?

distance from the sun is perfect. not too hot, not too cold.

What does the "Goldilocks Zone" allow for?

liquid H2O

What is liquid H2O considered?

THE life-supporting molecule.

When does water reach its maximum density? What else does it have at this temperature?

near 4 degrees C (3.98) & also has a high specific heat.

Why are the two properties of water (max density and high specific heat) especially significant to aquatic ecosystems?

it allows for nutrient turnover and oxygen distribution

What does the properties of water arise from?

mostly from its molecule structure.

-polar covalent bond produces "double" dipolar molecule

What does the "double" dipolar molecule allow water to do?

allows for extensive hydrogen bonding among molecules. each water molecule can H-bond to 4 other water molecules.

What does water form around ions and polar compounds?

spheres of hydration

What is less soluble than polar compounds in water? Why?

nonpolar compounds are far less soluble in water because sphere of hydration cannot form.

What does the H bonding in water allow it to have in terms of heat?

high specific heat

-high latent heats of melting and evaporation.

What is specific heat?

energy (calories) required to raise one gram of water 1 degree C

How much energy is used to change ice to water?

80 cal

How much energy is used to change water to steam?

540 cal

Overall, water has a high?

thermal stability

In a summary, what are 4 water properties?

H-bonding

spheres of hydration

high specific heat

universal solvent

What helps explain why ice floats in water?

water is most dense at 3.98 degree C. therefore ice is less dense than water.

What is the big result for water being at its highest density at 4 degrees C?

nutrient turnover

Is there more saline or fresh water on the eart?

saline= 97.5%

fresh= 2.5%

Of the freshwater, what is the water distribution?

glaciers > ground > surface

Of surface water, what is the distribution?

lakes > swamps > rivers/streams ~ air

What is the hydrologic cycle?

the water cycle that is powered by solar energy

What are the 3 phases of hydrologic cycle?

precipitation

evaporation

surface + groundwater runoff

What does all 3 phases of the hydrologic cycle involve?

each phase involves transport, temporary storage and change in physical state of water.

During the precipitation phase, how long is H2O stored?

H2Ois stored in the atmosphere as water vapor for roughly 9 days.

After H2O is stored in the atmosphere for 9 days, what occurs?

the water returns to earth via rain, snow, sleet, hail, and condensation.

this is precipitation.

Over the ocean, is evaporation or precipitation greater?

evap >> precip

-technically a net LOSS.

Over land, is evaporation or precipitation greater?

precip >> evap

-technically a net GAIN.

What is interception

water not making it all the way to land.

-water clings to plants and other surfaces.

What is surface runoff?

Water that does not infiltrate into the ground.

examples: puddles

surface detention or depression storage.

What is vadose water?

water in soil / above water table

How long can water be stored in the vadose zone?

months

Vadose water may percolate to?

the water table where permeable soils are saturated.

After the water table, what occurs?

the water becomes ground water

How long can water be stored as ground water?

hundred to thousands of years.

What is interflow?

ground water movement into and through overlying unsaturated soils.

How does vadose water move in the soil?

moves vertically (percolation via gravity) to water table

OR flows laterally to nearest outlet or stream drainage channel.

What are the two types of vadose flow?

-subsurface stormflow

-return flow

What is subsurface stormflow?

when permeable surface soils overlay shallow impermeable surfaces "lenses"

What is return flow?

when subsurface flow encounters saturated soil areas or impermeable surfaces and is directed to surface.

H2O below water table is? What does this account for?

ground water.

-this accounts for stable base flow of many streams.

What are the five types of water flow?

groundwater flow

subsurface stormflow

return flow

interflow

overland flow

What do the five types of flow provide water for?

-provides water for intermittent streams (no flow year round)

-base flow for permanent streams (flows year round)

What does evaporation do to the temperature of the earth?

evaporation cools the environment.

What does condensation do to the temperature of the earth?

heats the environment

How much precipitation returns to the atmosphere by evaporation?

>80% of precip

Where does evaporation come from?

-much water evaporates as precipitation occurs.

-intercepted H2O also evaporates.

-From water surfaces: runoff, streams, lakes, wetlands, etc.

What does evaporation remove from the surroundings?

it removes heat from surroundings= evaporative cooling.

What are the two types of evaporation?

transpiration

sublimation

What is transpiration?

water moves from soil, through plant, then evaporates through leaf stomates.

How can a lot of water be moved from the soil to the atmosphere?

via transpiration.

What is sublimation?

solid to gas

-water as snow + ice turns into atmospheric water without a liquid phase.

What is evapotranspiration?

transfer H2O from earth's surface to atmosphere by sum of evaporation, sublimation, transpiration.

What causes transpiration to occur?

adhesion + cohesion

H2O from roots to top of tree with no energy spent.

How much water does the plant use during transpiration? How much evaporates?

plant uses 10% for photosynthesis.

90% evaporates.