APES Notes 1.7 - Hydrologic (Water) Cycle

Summary

In this educational video, Mr. Smeeds explores the hydrologic cycle, detailing how water transitions between solid, liquid, and gas states, and moves between various reservoirs such as the atmosphere, bodies of water, and underground aquifers. Key processes like evaporation, transpiration, and precipitation are explained, emphasizing the sun's role in driving the cycle. The importance of understanding these processes for human use of freshwater is highlighted, along with the environmental implications of runoff and infiltration.

Takeaways

• 🌊 The hydrologic cycle, also known as the water cycle, involves the movement of water in different states between various sources and reservoirs.
• 💧 Water's state of matter, whether solid, liquid, or gas, is crucial in understanding its movement within the cycle.
• 🌤️ Precipitation, such as rain, represents water transitioning from a gaseous state in the atmosphere to a liquid state on Earth's surface.
• 🌍 The hydrologic cycle is driven by solar energy, which causes water to evaporate from bodies of water and transpire from plants.
• 🌊 The largest reservoir of water on Earth is the ocean, while smaller but significant freshwater reservoirs include polar ice caps, glaciers, and groundwater.
• 🌿 Transpiration is the process by which plants draw water from the ground and release it into the atmosphere through stomata in their leaves.
• 🌡️ Evapotranspiration is the combined process of evaporation and transpiration, representing the total water vapor released into the atmosphere from an ecosystem.
• 💧 Runoff occurs when precipitation flows over the Earth's surface and eventually reaches bodies of water, contributing to surface water reservoirs.
• 🌱 Infiltration is the process where water from precipitation soaks into the ground, replenishing aquifers and groundwater supplies.
• 🌳 The permeability of the ground cover significantly affects the amount of water that can infiltrate and recharge groundwater reservoirs.

Q & A

What is the hydrologic cycle?

The hydrologic cycle is the movement of water in different states between various sources and reservoirs, driven by energy from the sun.

How does precipitation relate to the hydrologic cycle?

Precipitation is a part of the hydrologic cycle where water in the atmosphere condenses into clouds and falls back to Earth as liquid, moving from the atmospheric reservoir to the surface water or groundwater reservoirs.

What are the two key reservoirs water might move to after precipitation?

After precipitation, water might move to surface water bodies or infiltrate into the ground to become groundwater.

What is the role of the sun in the hydrologic cycle?

The sun provides the energy necessary to drive the hydrologic cycle, particularly in processes like evaporation, where it warms water bodies causing water to evaporate and enter the atmosphere as a gas.

What is the largest reservoir of water on Earth?

The largest reservoir of water on Earth is the ocean.

Why are polar ice caps, glaciers, and groundwater important?

Polar ice caps, glaciers, and groundwater are important because they are significant freshwater sources that humans can use for agriculture and drinking, unlike the saltwater from the ocean.

What is transpiration and how does it relate to the hydrologic cycle?

Transpiration is the process where plants draw water from the ground via their roots and release it as water vapor through their leaves, contributing to the water cycle by moving water from the liquid state on Earth to the gaseous state in the atmosphere.

What is evapotranspiration and how does it contribute to the water cycle?

Evapotranspiration is the sum of water lost to the atmosphere from both evaporation and transpiration. It represents the total amount of water that leaves an ecosystem in the form of water vapor, driven by the sun's energy.

What are the two possible outcomes for precipitation when it reaches the Earth's surface?

When precipitation reaches the Earth's surface, it can either flow across the surface as runoff into a body of water or it can infiltrate into the ground and become part of the groundwater.

How does the permeability of the ground cover affect groundwater recharge?

The permeability of the ground cover affects groundwater recharge by determining how easily water can infiltrate the soil and reach underground aquifers. More permeable surfaces, like those covered by grass and soil, allow for greater infiltration and recharge of groundwater.

Why is runoff important for human use, but also a potential problem?

Runoff is important for human use because it replenishes surface bodies of water, which are crucial for drinking and agriculture. However, it can also be a problem because as it flows over the surface, it can pick up pollutants, which then get carried into water bodies, potentially causing environmental and health issues.

Outlines

00:00

💧 Understanding the Hydrologic Cycle

Mr. Smeeds introduces the hydrologic or water cycle, emphasizing its importance as a biogeochemical cycle. He outlines the objective to explain the steps and reservoir interactions within the cycle. The discussion focuses on the states of matter water travels in and the reservoirs it moves between, such as precipitation from the atmosphere to earth's surface as liquid. The video highlights the significance of the sun's energy in driving the cycle, with examples of water reservoirs including oceans, polar ice caps, glaciers, and groundwater. The importance of fresh water sources for human use is also stressed.

05:01

🌿 Exploring Evapotranspiration and Its Impact

The script delves into the processes of evaporation and evapotranspiration, explaining how water transitions from liquid to gas form in the atmosphere. Transpiration, the process by which plants absorb water and release it through stomata, is detailed. The concept of evapotranspiration, which encompasses both evaporation from surfaces and transpiration from plants, is introduced as a key component of the water cycle. The video also addresses the processes of runoff and infiltration, explaining how water either flows over surfaces or seeps into the ground, replenishing surface and groundwater reservoirs. The importance of permeability for groundwater recharge and the potential pollution issues associated with runoff are also discussed.

Keywords

💡Hydrologic Cycle

The hydrologic cycle, also known as the water cycle, is the continuous movement of water on, above, and below the surface of the Earth. In the video, it is described as the movement of water in different states between various sources and reservoirs. The cycle is crucial for understanding how water is distributed and transformed across the planet, affecting ecosystems, climate, and human activities.

💡Reservoirs

Reservoirs in the context of the hydrologic cycle refer to the storage locations for water, such as oceans, lakes, rivers, and underground aquifers. The video explains that water moves between these reservoirs through various processes, emphasizing the importance of understanding both the state of matter of the water and the direction of its movement.

💡Precipitation

Precipitation is water released from the atmosphere in forms such as rain, snow, sleet, or hail. In the video, it is described as a process where water moves from the gaseous state in the atmosphere to the liquid state on Earth's surface, highlighting the transition from one reservoir to another.

💡Evaporation

Evaporation is the process by which water changes from a liquid to a gas or vapor and enters the atmosphere. The video explains that this is driven by the sun's energy, which heats the water at the surface of bodies of water, causing it to turn into vapor and rise into the atmosphere.

💡Transpiration

Transpiration is the process by which plants release water vapor into the atmosphere through small pores called stomata in their leaves. The video describes how plants use this process to draw water from the ground, contributing to the hydrologic cycle by releasing water vapor that has been absorbed from the soil.

💡Evapotranspiration

Evapotranspiration is the sum of evaporation and transpiration. It represents the total amount of water vapor that enters the atmosphere from the land surface and plants. The video emphasizes that both processes are driven by the sun and are critical for the movement of water in the hydrologic cycle.

💡Infiltration

Infiltration is the process by which water from precipitation soaks into the ground and eventually reaches underground water stores called aquifers. The video explains that this process is essential for replenishing groundwater, which is a vital freshwater source for human use, especially in arid regions.

💡Runoff

Runoff is the flow of water that occurs when excess stormwater, meltwater, or other sources of water flow over land and into surface waters such as rivers, lakes, or oceans. The video discusses how runoff contributes to the replenishment of surface water bodies, which are important for human consumption and agriculture.

💡Polar Ice Caps and Glaciers

Polar ice caps and glaciers are large masses of ice found in the polar regions and high mountain ranges. The video mentions these as important freshwater reservoirs, emphasizing their role in the hydrologic cycle and the availability of freshwater for human use.

💡Aquifers

Aquifers are underground layers of water-bearing permeable rock or unconsolidated materials from which groundwater can be extracted using a water well. The video explains that infiltration contributes to the recharge of aquifers, which are significant for providing water in areas where surface water is scarce.

💡Permeability

Permeability refers to the ability of a substance, usually rock or soil, to allow fluids to pass through it. In the context of the video, permeability is crucial for the infiltration process, as it determines how easily water can soak into the ground and replenish aquifers.

Highlights

Introduction to the hydrologic cycle as a biogeochemical cycle.

Objective to explain the steps and reservoir interactions in the water cycle.

The hydrologic cycle involves the movement of water in different states between sources and reservoirs.

Focus on the state of matter of water (solid, liquid, gas) and its movement between reservoirs.

Precipitation as an example of water moving from gas in the atmosphere to liquid on Earth's surface.

Reservoirs water might move to include surface water bodies or groundwater.

The hydrologic cycle is driven by energy from the sun.

The largest reservoir of water on Earth is the ocean.

Polar ice caps, glaciers, and groundwater are important freshwater sources.

Evaporation and evapotranspiration are key processes moving water from liquid to gas form.

Transpiration is the process by which plants draw water up from the ground and release it through leaves.

Stomata are the pores in plant leaves that facilitate transpiration.

Evapotranspiration is the sum of water lost through evaporation and transpiration.

Sun's energy drives both evaporation and transpiration.

Runoff and infiltration are processes that occur when precipitation reaches Earth's surface.

Runoff is the flow of water across the surface into bodies of water.

Infiltration is the process where water soaks into the ground and reaches aquifers.

Permeability of ground cover is crucial for groundwater recharge.

Runoff contributes to surface water bodies but can also carry pollutants.

Practice FRQ to explain relationships between concepts in a visual model of the water cycle.

Transcripts

hey everybody it's mr smeeds and today

we'll be covering topic 1.7

which is the hydrologic or water cycle

just like in all of the other

biogeochemical cycles we've covered

we'll be looking at how water moves

between sources and sinks

our objective for the water cycle is to

be able to explain the steps and

reservoir interactions

in the cycle and at the end of the video

we'll practice the scientific skill

of explaining differences between

environmental concepts

using a visual model so the hydrologic

cycle is the movement of water

in different states between different

sources and reservoirs

and so in this cycle we like to focus on

first of all what state of

matter that water is traveling in

whether that's solid liquid or gas

but then also where is the water moving

so

what reservoir is it leaving and what

reservoir is it entering

so for example we could look at

precipitation which we

probably know already as rain and that

is going to be

water moving from a gas in the

atmosphere as it condenses together into

clouds

and then eventually falls back down to

earth as a liquid so the reservoir it's

leaving as the atmosphere

and the reservoir it's entering is a

little bit trickier it's going to be

hitting earth's surface

and it could run off into a body of

water then it would be entering what

we'd call a surface water or a body of

water

or it could infiltrate into the ground

and it could become

groundwater so those are the two

reservoirs water might be moving to

really important to know that the

hydrologic cycle is driven by energy

from the sun

this is kind of a tricky concept but

think about a body of water

as the sun hits that body of water

that's going to cause the water at the

surface to warm

and eventually turn into a gas and

evaporate

the largest reservoir of water on earth

is the ocean that's important to know

but two smaller reservoirs are polar ice

caps glaciers and ice caps found on

mountains

as well as ground water these are very

important because they're fresh water

sources

so humans can't use salt water from the

ocean for things like agriculture or

drinking

but we can use these fresh water sources

so even though they're a lot

smaller it's really important that we

remember these are our

key freshwater sources now we'll talk

about evaporation

and evapotranspiration so these are the

two key

sources or processes that move water

from a liquid form

on earth into a gas form in the

atmosphere

sometimes we call this the vaporization

of water because it's

liquid water transforming into a vapor

or gas that enters the atmosphere so

transpiration

is this process where plants are going

to draw water

up from the ground via their roots and

up into their stem and their leaves and

other

places in the plant that need water so

they do this with a really neat trick

and they are going to use these little

pores in their leaves called stomata

so the stomata open up so if we look at

the diagram here we can see these

pores basically in the leaf are going to

open and water vapor

is going to evaporate due to the sun's

energy what that does is creates a

low pressure system where the leaf

has a lower water pressure than the

roots and that's going to draw water

up from the roots to replace that water

in the leaf that evaporated

so in the diagram here we can see the

water that's in the ground will be drawn

up the roots up the stem and to the

leaves because we have a low water

pressure in the leaves

as they open their stomata and allow the

sun's energy to cause some

transpiration so again as a summary

transpiration

is the process of a plant drawing water

up from the ground via its roots

by allowing some of the water in its

leaves to evaporate

now we have a concept called

evapotranspiration

and evapotranspiration is just a way to

add up the total amount of water

leaving an ecosystem by both

transpiration

and evaporation so if we look at the

diagram the water that evaporates from

the soil or from bodies of water

combined with the water that leaves

plant stomata

via transpiration would be considered

evapotranspiration

really important to remember that both

processes are driven by the sun

so when the sun's rays strike the soil

some of the moisture in that soil will

be heated up and it will evaporate as a

gas in the atmosphere

and same thing with the leaf when the

leaf has its leaves warmed by the sun

and it opens its stomata some of the

liquid water in that leaf

will evaporate as a gas and again that's

how the leaf is going to actually draw

more water up from the roots

and finally we'll talk about runoff and

infiltration

so when precipitation falls to earth's

surface it can do one of two things it

can either flow across the surface until

it reaches

a body of water as runoff or it can

slowly trickle into underground water

stores called aquifers

and we call that process infiltration so

we can look at the

diagram here and we can see that if the

water hits earth's surface

and just flows into a body of water we'd

call that surface runoff

but if it hits the ground and it's able

to soak into the ground and eventually

reach an

aquifer or an underground water storage

we would call that infiltration

now these two processes are very

important because they contribute water

to very important freshwater reservoirs

so runoff will recharge

surface bodies of water which are

important drinking sources for humans

and important sources for agriculture

but they'll also recharge groundwater

which can be especially important water

sources in dry areas where humans have

to use a well to drop water from the

ground

so remember that precipitation is going

to recharge groundwater

only if that water falling can

infiltrate

the soil so if we look at this diagram

here to help us understand that

if we have a surface that is covered by

grass and soil

that's going to allow a lot of the water

to infiltrate or to soak into the ground

and recharge those aquifers underground

but on the right hand diagram we have a

surface that's not very permeable

meaning it doesn't allow water to easily

trickle through

and so far more of that water is going

to leave the area as runoff

so permeability or the ability of

a ground cover to allow water to soak

through and

into the aquifers beneath it is really

important for groundwater recharge

runoff on the other hand is going to

eventually recharge surface waters it

will return water that fell as

precipitation

to a lake or a river or a pond and

that's an important source for humans to

use

but one drawback of this is that the

runoff

gathers pollutants on its way to the

surface body of water

and so we'll be talking about these

issues in a lot more depth when we get

to our water unit later in the year

our practice frq for topic 1.7 today

will cover the skill of explaining

relationships between concepts in a

visual model

so what i want you to do is take a look

at this diagram of the water cycle

and there are four different letters you

have a b c and d

i want you to choose one of those

letters and identify the process that's

being shown

then describe how water is moving from

one reservoir

to another reservoir by that process

all right everybody thanks for tuning in

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