Water Cycle | How the Hydrologic Cycle Works

00:06:47
https://www.youtube.com/watch?v=al-do-HGuIk

摘要

TLDRThis video explores Earth's water cycle, a critical process involving the movement and transformation of water across various states and locations. Water is a finite resource, continually cycling through processes like precipitation, evaporation, and transpiration. Water moves between stores such as clouds, oceans, and underground aquifers, supporting life by maintaining ecological and climatic balance. Understanding the water cycle involves examining its complexity, including how water infiltrates the soil, how it moves through plants via evapotranspiration, and how it eventually evaporates to restart the cycle. The video emphasizes the importance of studying the water cycle to grasp the intricacies of Earth's environmental systems.

心得

  • 💧 Freshwater is millions of years old, continuously cycled on Earth.
  • 🔄 The Water Cycle is a series of flows and storages, essential for life.
  • ☁️ Clouds play a critical role in the water cycle with precipitation.
  • 🌱 Plants use water from the soil and release it via transpiration.
  • 💧 Precipitation can be rain, snow, or hail, depending on conditions.
  • 🏞️ Water in the ground moves towards rivers and oceans slowly.
  • 🔍 Scientists study the water cycle to understand Earth’s ecosystem.
  • 🔥 Evaporation is vital, converting water to vapor due to solar heat.
  • 🌨️ Rain and snow are integral to maintaining freshwater sources.
  • 🌿 Evapotranspiration is key for plant and earth interaction.
  • 🌊 Oceans hold 70% of Earth’s water, playing a pivotal role.
  • 💦 Understanding water cycle helps manage water resources effectively.

时间轴

  • 00:00:00 - 00:06:47

    All Earth's water is part of a continuous cycle, existing for millions of years, and vital for life as it loops from the atmosphere to land and back. The water cycle, a series of flows and stores, includes processes like precipitation, collection, and evaporation. Scientists study its complexity to understand its functions and impact.

思维导图

Mind Map

常见问题

  • What is the water cycle?

    The water cycle is the continuous movement and transformation of water between various storage locations such as oceans, rivers, and the atmosphere.

  • Why is water essential for life on Earth?

    Water is essential for life because it supports various biological and ecological processes and maintains the Earth’s climatic systems.

  • What forms can precipitation take?

    Precipitation can occur as rain, snow, hail, or sleet, representing water in liquid, solid, or gaseous forms.

  • How does water infiltrate the ground?

    Precipitation can infiltrate the ground if the soil is not saturated, percolating through the soil and rock particles into underground aquifers.

  • What happens to groundwater?

    Groundwater can move laterally through soil and rock, eventually discharging into rivers, lakes, or the sea.

  • What is evaporation?

    Evaporation is the process of water turning from liquid to vapor due to solar heat, moving from surfaces into the air.

  • What is transpiration in the water cycle?

    Transpiration is the process where plants absorb water from the soil and release it as vapor through their leaves.

  • How do clouds form?

    Clouds form when evaporated water vapor condenses around dust and smoke particles in the atmosphere.

  • What does 'evapotranspiration' mean?

    Evapotranspiration refers to the combined process of evaporation from the surface and transpiration from plants.

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  • 00:00:00
    ♫MUSIC♫
  • 00:00:13
    ANNE THOMPSON: All the water on Earth today, every drop, is all
  • 00:00:17
    the water there has ever been on the planet. Freshwater is
  • 00:00:21
    actually millions of years old. The same water, flowing in a
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    continuous loop- falling as rain and snow from clouds to the
  • 00:00:29
    Earth's surface, running in rivers, pooling in ponds,
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    flowing from faucets, irrigating crops, traveling through plants,
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    generating power, eventually evaporating into the air and
  • 00:00:46
    condensing into clouds again.
  • 00:00:49
    ANNA MICHALAK: Why is there life on Earth? The reason
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    there is life on Earth is because Earth has this
  • 00:00:55
    perfect water cycle.
  • 00:00:56
    THOMPSON: The Water Cycle, so simple even small children
  • 00:01:00
    understand the basics, yet so complex, the most advanced earth
  • 00:01:04
    scientists, hydrologists, geologists, and biogeochemists
  • 00:01:08
    are studying every part and process.
  • 00:01:11
    MARTHA CONKLIN: The Water Cycle is fascinating. It's something
  • 00:01:14
    that's around us all the time, and yet we don't
  • 00:01:19
    really understand it.
  • 00:01:20
    THOMPSON: How to summarize what is known about the Water Cycle?
  • 00:01:23
    With two words- flows and stores. The Water Cycle is a
  • 00:01:29
    series of flows of water between various water stores or
  • 00:01:32
    storages. Clouds in the atmosphere...
  • 00:01:36
    TOM HARMON: There's always a little bit of water in the
  • 00:01:37
    atmosphere. We talk about relative humidity- it's a humid
  • 00:01:40
    day, it's a dry day- either way, there's water, sometimes a
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    little, sometimes a lot.
  • 00:01:44
    THOMPSON: There's a lot of water in the oceans – 70% of all
  • 00:01:47
    the water on Earth, in the ice sheets and glaciers - two-thirds
  • 00:01:51
    of all the fresh water on Earth, in the snow packs atop mountains
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    like the Sierra Nevada, in the Great Lakes, in rivers and
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    streams, in reservoirs and watersheds, in wetlands, in the
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    soil, in and on plants and trees rooted in the soil, and beneath
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    the soil, in water tables and underground aquifers like the
  • 00:02:15
    Ogallala-High Plains, which runs underneath parts of eight
  • 00:02:18
    states, from South Dakota to Texas. All this storage is
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    temporary. Water, in all its forms, is always in flux and
  • 00:02:28
    always moving. And there's a name for every kind of movement
  • 00:02:32
    in the Water Cycle starting with precipitation.
  • 00:02:35
    MICHALAK: Precipitation is the process of water falling onto
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    the surface of the Earth. You can have precipitation in many
  • 00:02:42
    forms- rain, snow, hail.
  • 00:02:44
    THOMPSON: Rain is falling water in liquid form. Snow,
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    ice, hail and sleet are falling water in solid, or frozen form.
  • 00:02:54
    Fog and mist? Falling water in gas or vapor form. Precipitation
  • 00:03:01
    that falls directly into the oceans becomes part of surface
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    ocean and can be churned by wave and wind action into ocean
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    currents. Rain and snow that falls directly on rivers and
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    streams becomes one part of stream flow. Rain that falls
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    onto land takes a different path to the river as does the
  • 00:03:21
    snow and ice that falls and collects on mountaintops
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    when temperatures warm.
  • 00:03:26
    CONKLIN: When snow melts, some of it runs through the snowpack
  • 00:03:29
    and goes into small streams, tributaries that feed
  • 00:03:33
    into large rivers.
  • 00:03:35
    THOMPSON: What about the precipitation that falls on and
  • 00:03:38
    over land? Some is intercepted by vegetation -
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    plants and trees.
  • 00:03:43
    HARMON: Like you might imagine, someone in a game of football
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    intercepting a pass, these are raindrops trying to come to the
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    ground, and leaves on the tree intercept them before they
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    hit the ground.
  • 00:03:52
    THOMPSON: And the precipitation that does hit the ground? It can
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    run off if the ground is hardscaped - covered with
  • 00:03:58
    asphalt or concrete- or if the soil is too wet, or saturated to
  • 00:04:02
    absorb more water, like an over soaked sponge. Otherwise,
  • 00:04:07
    precipitation infiltrates the soil surface, percolates
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    into the ground.
  • 00:04:12
    HARMON: Think of it as the water percolating through your
  • 00:04:15
    coffee grounds in the morning. Gravity continues to pull it
  • 00:04:17
    downwards so it will move through.
  • 00:04:19
    THOMPSON: Through the topsoil, into spaces between soil and
  • 00:04:23
    rock particles, down to bedrock, and further, into fractures,
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    into deep underground aquifers. Even groundwater here
  • 00:04:32
    is moving sideways, or laterally, discharging toward a
  • 00:04:36
    river, lake or the sea, generally the deeper the flow,
  • 00:04:40
    the slower the flow.
  • 00:04:42
    CONKLIN: Some of that fractured water might take a very long
  • 00:04:45
    time, thousands to millions of years, to get out.
  • 00:04:48
    THOMPSON: And how does water get back out into
  • 00:04:50
    the atmosphere? It evaporates, is turned from a liquid
  • 00:04:54
    into a gas or vapor, by the heat of the sun.
  • 00:04:57
    MICHALAK: If you put a bit of water into a bowl and you set it
  • 00:05:00
    outside on a sunny day, it's going to disappear. It's still
  • 00:05:03
    water, it's just in the form of a gas rather than in the form
  • 00:05:06
    of a liquid.
  • 00:05:08
    THOMPSON: Water evaporates from every wet surface – even from
  • 00:05:10
    wet air. Some rain and snow evaporates into the air while
  • 00:05:14
    falling. Water evaporates through our respiration and
  • 00:05:18
    perspiration and from plants, through transpiration. Trans
  • 00:05:24
    means through or across. Plant roots draw up groundwater.
  • 00:05:29
    MICHALAK: And plants pull that water up through their stems
  • 00:05:33
    into their leaves and then release it back out
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    through evapotranspiration.
  • 00:05:37
    THOMSPON: Evaporanspiration, a spelling bee worthy term for
  • 00:05:41
    evaporation from soil and water surfaces, plus transpiration
  • 00:05:44
    from plants. Evaporated water molecules are tiny enough to
  • 00:05:49
    flow into the air. Mix with smoke and dirt particles in the
  • 00:05:52
    atmosphere. Cool, condense, into visible masses of water vapor –
  • 00:05:58
    clouds. Winds move clouds into colder air, water droplets
  • 00:06:03
    collide and merge, grow bigger and heavier, until they
  • 00:06:06
    are so heavy, they fall again as rain or snow, sleet or hail.
  • 00:06:11
    Precipitation. Collection. Runoff. Interception.
  • 00:06:18
    Infiltration. Percolation. Discharge. Transpiration.
  • 00:06:24
    Evaporation. Condensation. The Water Cycle.
  • 00:06:30
    ♫MUSIC♫
标签
  • water cycle
  • precipitation
  • evaporation
  • transpiration
  • aquifers
  • clouds
  • water storage
  • environmental science
  • groundwater
  • water movement