24 Questions
What percentage of fresh water on Earth is solid?
More than 90%
Why does salt water require a lower temperature to freeze?
Because the salt in salt water does not freeze with the water
What is the primary reason why snow accumulates in mountain regions?
Because the snow that falls never gets a chance to melt
What is the term used to refer to the large ice masses at the poles?
Polar icecap
What happens to the air spaces in the snow as it becomes compacted?
They are squeezed out
What is the average thickness of the Antarctic ice sheet?
More than 2 km
What is the term used to describe the floating ice that breaks off from an ice shelf?
Iceberg
Why does ocean water freeze at a lower temperature than fresh water?
Because of its higher salinity
What is the reason behind ocean ice becoming frozen fresh water?
Because the salt in salt water does not freeze with the water
What is the process that leads to the formation of a glacier?
Compacted snow changing into a solid mass of ice
What happens to icebergs as they float on the ocean?
They melt, change shape, roll over, and eventually become part of the ocean water
What is the characteristic that distinguishes an ice sheet from a mountain glacier?
Scale, with ice sheets being much larger
Why do glaciers and ice sheets primarily exist in polar regions and high mountains?
Because temperatures are below freezing for most of the year, allowing snow to accumulate
What is the estimated volume of frozen fresh water contained in glaciers and ice sheets?
More than 40 million km3
What is the result of the salt in ocean water not freezing with the water?
Ocean ice becomes frozen fresh water
What is the purpose of gravity in the formation and movement of glaciers?
Gravity influences the slow movement of glaciers down a mountain slope
What is the driving force behind the water cycle?
The Sun's thermal energy
What is a watershed, and how can it be visualized?
A watershed is an area of land where all the water eventually drains into one main water body, such as a stream, river, wetland, lake, or ocean. It can be visualized as making a small model boat that is unsinkable and could move downstream with a river's current all the way to an ocean.
What is the role of high points in the land, such as mountain ridges, in directing water flow?
They create natural 'divides' that direct where water flows.
What is the name given to the process of water changing states as it moves from Earth's surface into the atmosphere and back to Earth again?
The water cycle
How do mountain chains or long areas of high land affect the boundaries of major watersheds on the continents?
They mark the boundaries of major watersheds on the continents.
What is the term used to describe the boundary that directs where water flows?
A divide
How many ocean watersheds are there in North America?
Five
What is the term used to describe the Rocky Mountains in relation to watersheds?
The Great or Continental Divide
Study Notes
Solid Water
- All solid (frozen) water on Earth is fresh water.
- Ocean water can freeze, but it requires a lower temperature than fresh water to become ice.
- The average freezing temperature for ocean water is –1.8°C.
- Because salt in salt water doesn't freeze with the water, all ocean ice becomes frozen fresh water.
Ice and Snow in Polar Regions and Mountains
- Most fresh water in polar regions and on top of high mountains exists in a solid state as ice and snow.
- Glaciers and ice sheets contain more than 40 million km³ of frozen fresh water.
Mountain Glaciers
- In mountain regions, temperatures are often below freezing, and snow accumulates over centuries, producing a heavy and thick mass.
- Over time, the snow in lower layers becomes compacted, squeezing out air spaces, and changes into a solid mass of ice.
- A glacier is a mass of ice and overlying snow that moves slowly down a mountain slope under gravity.
Ice Sheets
- An ice sheet is a large glacier that covers the land.
- There are only two large ice sheets on Earth, one in Greenland and one in Antarctica.
- Ice sheets form in the same way as mountain glaciers, but on a much larger scale.
- The Antarctic ice sheet has an average thickness of more than 2 km.
Ice Shelves and Icebergs
- Because ice floats, when an ice sheet reaches the ocean, the ice may float on the water.
- The floating ice is called an ice shelf.
- Large sections of an ice shelf that break off are called icebergs.
- As they float, icebergs melt, change shape, roll over, and eventually become part of the ocean water.
Solid Water
- All solid (frozen) water on Earth is fresh water.
- Ocean water requires a lower temperature to freeze than fresh water, with an average freezing temperature of -1.8°C.
- Salt in salt water does not freeze with the water, so ocean ice becomes frozen fresh water.
Glaciers and Ice Sheets
- Glaciers are formed when snow accumulates over centuries, becomes compacted, and changes into a solid mass of ice.
- Ice sheets are large glaciers that cover the land, with only two existing on Earth, in Greenland and Antarctica.
- The Antarctic ice sheet has an average thickness of over 2 km.
Ice Shelves and Icebergs
- When an ice sheet reaches the ocean, the ice may float on the water, forming an ice shelf.
- Large sections of an ice shelf that break off are called icebergs, which melt, change shape, and roll over as they float.
The Water Cycle
- The water on Earth is constantly changing state, with at least 5 L of every 100 000 L of Earth's total water cycling into another state every minute.
- The water cycle is driven by the Sun's thermal energy and involves the processes of evaporation, condensation, and precipitation.
Watersheds
- A watershed is an area of land where all the water eventually drains into one main water body, such as a stream, river, lake, or ocean.
- Activities that affect water in one part of the watershed have an effect downstream in the watershed.
- North America has five ocean watersheds: Arctic, Atlantic, Gulf of Mexico, Hudson Bay, and Pacific.
This quiz covers the properties of fresh water and ocean water, including their freezing temperatures and the formation of ice and snow in polar regions and mountains.
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