2.1.1 The concepts of system and mass balance

Question 1

What are some inputs/outputs and stores?

Answer 1

Input - precipitation
Output - evaporation/flow
store - cloud

Question 2

What is the global water cycle ?

Answer 2

At a global scale, there is a fixed amount of water in the Earth-atmosphere system,
amounting to about 1,385 million cubic kilometres in volume.

This water is either held in one place of several stores or is being transferred between them via a series of flows operating over varying timescales.

World water is a closed system.

Question 3

What are the inputs within the global water cycle?

Answer 3

Input - the addition of nutrient and /or energy into a system from outside

Question 4

What are the outputs within the global water cycle?

Answer 4

Output - material or energy moving from the system to outside

System - a set of interrelated components working together towards some kind of process/

Question 5

What are the stores and flows within the global water cycle?

Answer 5

Flows - a form of linkage between one store and another that involves movement of energy or mass

store - a part of the system where energy/mass is stored or transformed

Question 6

What makes the global water cycle a closed system?

Answer 6

Global water stores include the atmosphere (store - contains moisture) and the ocean, there are humorous terrestrial (land/store/moisture) stores too, including the soil,rivers, lakes , reservoirs and vegetation.

A water flow entering a store is called an input.
Flows leaving a store is called output
The global hydrological cycle as a whole is a closed system
This means it does not have any external inputs or outputs operating across the system boundary. The system mass balance does not change over time

Refer to chapter 1 - coastal system is an open system

Question 7

Why are ecosystems such as ponds regarded as an open System?

Answer 7

Input

Precipitation
Surface flow
Infiltration

Output

Evaporation (the sun)

For example : seeds carried by the winds - less surface flow - might act as a barrier - but there will more evaporation/ evapotranspiration

Question 8

What is the difference between water being stored in the hydrosphere, lithosphere, atmosphere and cryosphere?

Answer 8

Water is stored within four major physical systems- the lithosphere (land), hydrosphere (liquid water), cryosphere (snow and ice ) and atmosphere (air)

Water is trapped in air and in all of them essentially.

Question 9

The cryosphere consists of what areas?

Answer 9

The proportion of global water that is stored in solid form as ice is called the cryosphere.

The cryosphere consists of those areas of the earth where water is frozen into snow or ice, including ice sheets , ice caps , alpine glaciers , sea ice and permafrost.

Question 10

Why is groundwater stored? What type of lithology allows for this to occur?

Answer 10

aquifer - permeable rock that stores water e.g chalk

Porosity - is any rock / material that has pores or gaps in it but can store water

Clay and sand are more porous than limestone because they have small gaps.

Limestone - there is no porosity as it has bedding planes.

Question 11

What is residence time ?

Answer 11

Residence Time = is defined as the amount of water in a store divided by
either the rate of addition of water to the store or the rate of loss from it

Cryosphere has the longest residence time of 150 000 years

Question 12

How can the cryosphere store change over a short-term period (seasonal)?

Answer 12

Cryosphere stores can vary in size naturally over different timescales.

permafrist 
sea ice 
ice caps 
ice sheets 
alpane glaciers

Question 13

what can happen in short term changes and in long term changes ?

Answer 13

Short term changes that can occur in the cryosphere is in (summer ) it melts annually:
Ice sheets, alpine glaciers and sea ice

Long term changers would be ice caps and permafrost.

Accumulation is the build up of snow and ice - freezing
Ablation is the change from solid ice to liquid or water vapour when temp rises above 0 degrees celsius

Seasonal variations in levels of ice accumulation (freezing) and ablation ( melting)
Bring cyclical fluctuations in water storage in areas such as antarctica.

This system is described as a steady-state equilibrium. This means that the system maintains balance when viewed over the longer term( there will be a trigger )

However, evidence suggests that these and other cryospheric water stores may actually be expecting a permanent reduction in size because of anthropogenic (human) climate change.

Question 14

How can the cryosphere store change over a long-term period (millenia)?

Answer 14

Long term changes in the cryosphere storage are significant and far long lasting changes in water storage have occurred naturally in the distant past.

Question 15

What is Snowball earth ?

Answer 15

Geologists believe that the Earth may have become a giant ‘snowball’ during two distinct ice ages, which occurred around 650-750 million years ago. Cryospheric storage would have been much greater than it is today

Scientists in the Antarctica have drilled down into layers of ice over 400 000 years old

Snowball earth , hothouse earth , changes in earth’s orbit and axis and tectonic movements influenced the cryosphere storage of water.

Question 16

What is the hot house earth ?

Answer 16

In contrast to ‘snowball’ Earth, about 65 million years ago, ‘hothouse’ conditions meant the poles were probably free of ice – and crocodiles lived above the
Arctic Circle

Question 17

What are the changes in the earth orbit and axis ?

Answer 17

Firstly, every 100,00 years the Earth’s orbit changes from spherical to elliptical, changing solar input.

Second, the Earth’s axis is currently tilted at 23.5°, but this changes over a 41,000 –year cycle, between 22° and 24.5°, also affecting solar input.

Third, the Earth’s axis wobbles, changing over every 22,000 years, bringing further variations in solar input

Question 18

What are the earth’s tectonic movements ?

Answer 18

Such as Antarctica’s arrival at the south pole and the subsequent formation of the Antarctic ice sheet – have also had an important influence on changing cryosphere storage

Question 19

What is the monsoon and how can it bring about short-term seasonal changes to rainfall amounts?

Answer 19

Monsoons are short term seasonal changes in rainfall transfers.

The season that rains from may to september in south asia is called monsoon.

Monsoon is the seasonal change of wind direction which brings huge storms. In Asia, monsoons are very common. Monsoon season begins in may in asia and countries such as bangladesh, india , nepal pakistan and sri lanka suffer from heavy rainfall and storms