[General Science] Condensed Notes.pdf

# GENERAL SCIENCE POINTERS ## BASIC CONCEPTS AND LAWS - Botany: The study of plants. - Zoology: The science that covers animals and animal life. - Genetics: The study of heredity. - Medicine: The science of diagnosing, treating, and preventing illness, disease, and injury. # Science and Technology...

# GENERAL SCIENCE POINTERS ## BASIC CONCEPTS AND LAWS - Botany: The study of plants. - Zoology: The science that covers animals and animal life. - Genetics: The study of heredity. - Medicine: The science of diagnosing, treating, and preventing illness, disease, and injury. # Science and Technology ## Science - is a systematic study that is concerned with facts and principles, and methods that could be observed in our natural or physical and social environment - comes from the Latin word 'scire' that means 'to know' - is both a body of knowledge and a process - a way of thinking, a way of solving problems ## The Branches of Science ### THE PHYSICAL SCIENCES - **Physics:** The study of matter and energy and the interactions between them - Physicists study such subjects as gravity, light, and time - Albert Einstein, a famous physicist, developed the Theory of Relativity. - **Chemistry:** The science that deals with the composition, properties, reactions, and the structure of matter - The chemist Louis Pasteur discovered pasteurization, which is the process of heating liquids such as milk and orange juice to kill harmful germs. - **Astronomy:** The study of the universe beyond the Earth's atmosphere. ### THE EARTH SCIENCES - **Geology:** The science of the origin, history, and structure of the Earth, and the physical, chemical, and biological changes that it has experienced or is experiencing. - **Oceanography:** The exploration and study of the ocean. - **Paleontology:** The science of the forms of life that existed in prehistoric or geologic periods. - **Meteorology:** The science that deals with the atmosphere and its phenomena, such as weather and climate. ### THE LIFE SCIENCES (BIOLOGY) ## Scientific Method - is the logical method used by scientists to acquire knowledge that is used to explain different phenomena in nature - a thing observed by the senses is called a phenomenon; a scientifically tested observation is called a fact. - has six basic steps: 1. **Identify and clearly state the problem.** Questions arise from something observed as unusual; a problem that is specific, measurable, and attainable is identified. 2. **Gather information pertinent to the problem.** This is done by recalling past experiences concerning the problem, interviewing people who are knowledgeable of the problem, and researching in libraries and research centers. 3. **Formulate hypothesis.** Based on information or data gathered, an 'educated guess' can be made. 4. **Test the hypothesis.** Carrying out experiments. 5. **Draw a generalization or conclusion.** - Conclusion: a statement about the result of the experiment. - Law: a statement which describes what happens but does not explain the cause of the occurrence. - Theory: hypothesis that can be explained from observations. 6. **Apply the principle (conclusion) to other situations.** ## Controlled experiment - manipulating one of the conditions or factors that may affect the result of an experiment. - **1) Trials:** - number of times experiment is repeated. - **2) Controls:** factors that are kept constant throughout the experiment - **3) Variables:** - factors that change during the experiment. - **Kinds:** - **Independent or experimental** - factors that are changed. - **Dependent** - factors that change as a result of changes in the independent variable. ## Technology - is defined as the application of scientific knowledge to practical purposes. - is an applied science. - kinds: 1. **Machines:** include tools, gadgets or devices that help us do activities faster and better 2. **Products:** materials produced or made through artificial or natural means. 3. **Processes:** include the ways of doing things. ## Measurement ### International System (SI) of Measurement - Measurement is the process of comparing a quantity with a chosen standard. - The International System (SI) is the system of units that scientists have agreed upon and is legally enforced in almost all parts of the world. - There are seven basic quantities in this system: | Quantity | Unit | | :---------- | :----------- | | Length | Meters (m) | | Mass | Kilograms (kg) | | Time | Seconds (s) | | Electric current | Amperes (amp) | | Temperature | Kelvin (K) | | Amount of substance | Moles | | Luminous intensity / light | Candelas | ### Metric Prefixes - Metric prefixes are pretty easy to understand and very handy for metric conversions. - All metric prefixes are powers of 10. | Prefix | Symbol | Factor | | :------ | :----- | :-------------------------- | | giga | G | $10^{9} = 1,000,000,000$ | | mega | M | $10^{6} = 1,000,000$ | | kilo | k | $10^{3} = 1,000$ | | hecto | h | $10^{2} = 100$ | | deka | da | $10^{1} = 10$ | | deci | d | $10^{-1} = 0.1$ | | centi | c | $10^{-2} = 0.01$ | | milli | m | $10{-3} = 0.001$ | | micro | μ | $10^{-6} = 0.000,001$ | | nano | n | $10^{-9} = 0.000,000,001$ | | pico | p | $10^{-12} = 0,000,000,000,001$ | ### Temperature - There are three temperature scales in use today, Fahrenheit, Celsius and Kelvin. - **Fahrenheit** is a scale based on 32 for the freezing point of water and 212 for the boiling point of water, the interval between the two being divided into 180 parts - $F= 9/5C+32$ - **Celsius** (C) is the scale based on 0 for the freezing point of water and 100 for the boiling point of water. - $C = 5/9(F-32)$. - **Kelvin** is the base unit of thermodynamic temperature measurement in the International System (SI) of measurement. - It is defined as 1/ 273.16 of the triple point (equilibrium among the solid, liquid, and gaseous phases) of pure water. - $K = °C +273$ ### Volume - Volume refers to the amount of space that an object occupies. #### VOLUME OF A REGULAR SOLID - A regular solid is one having length, width, and thickness or height - Volume is expressed in cubic units #### VOLUME OF A LIQUID - Liquid volume is also measured in cubic meters but the use of liter (L) is widely accepted. - A graduated cylinder is used to measure the volume of liquid. - Liquid Volume Equivalents: - $1dm³ = lliter (L)$ - $1 cm³ = a milliliter (mL)$ - $1000 cm³ = lliter$ #### VOLUME OF AN IRREGULAR SOLID - An irregular solid is one where a dimension cannot be measured in a single straight line. - The displacement method is used to determine its volume. ## Density - Density is the mass of the object per unit volume. - Substances differ in their densities. - Each substance has a specific density. - All materials with a density less than 1 g./cc (density of water) will float on water, and all those with density greater than 1 g/cc will sink. - $D= Mass / Volume (g/cc)$ ## Force - normally refers to the measurement of a push or a pull - anything that changes the speed and direction of moving objects or that which causes a stationary object to start moving in a straight line ### Measuring force - Gravitational force is the pull that the earth exerts on all objects - Measured by the weight of an object. ### Types of forces - **Gravitational force** - downward force that the earth exerts on objects - **Inertia** - tendency of an object to remain at rest or maintain its motion unless disturbed by a force. - **Friction** - resists / opposes the relative sliding movement of two surfaces in contact with one another. - **Centripetal force** - drive a thing inward toward a center or rotation. It keeps an object moving in a circular path. - **Force of Gravity** - that which is acting on an object which enables it to exert an equal and opposite force on its support. - **Nuclear Force**- the strongest known force which holds together the protons and neutrons in the nucleus of an atom. - **Electromagnetic Force**-binds electrons to the atomic nucleus, atoms in the molecules, ions in solid matter, and molecules into liquids and solids.. ### Mass vs Weight - **Mass** indicates the quantity of matter in a material object. - Measured in a unit called kilogram. - Does not change. - **Weight** is the measure of the pull of gravity on an object. - Depends on the mass of the object and its distance from the center of the earth. - Expressed in N unit. 100g = IN. ### Work - Work is done only when the force applied to an object actually moves the object in the direction of the force. - $WORK = force \times displacement$ ### Calculating the amount of work - $W= F\times d $ - $W = (Newton)\times (meter) $ - $W = Newton-meter or joule$ ## Energy - The term energy is derived from the Greek word, energeial (en meaning in and ergon, meaning work). - Anything that is able to do work possesses energy. - The ability to do work or the ability to exert force on an object and make it move. ### Forms of energy - **Mechanical Energy:** - **kinetic** - energy possessed by an object or a body in motion - **potential** - energy possessed by a body because of its position or state - **Internal Energy** or **Thermal Energy:** total energy coming from the attractive and repulsive forces of all the particles or molecules in a body. - **Heat Energy** - energy which flows from one body to another due to a temperature difference between them, and the flow is always from the hotter to the colder body. - **Electrical Energy** - electricity is the energy of electrons flowing through conductors, like copper wires and aluminum wires. - **Chemical Energy** - energy stored in matter due to forces of attraction and to the arrangement of subatomic particles in atoms and of atoms in the molecules of substances. - **Radiant Energy** - energy of the electromagnetic waves, radio waves, infrared rays, visible light, ultraviolet rays, x rays and gamma rays. - **Nuclear Energy** - energy released from nuclear fusion or fission of atomic nuclei of heavy element or light element. ### Methods of heat transfer - **Conduction** - when the molecules in a heated material collide with other molecules and spread heat until it’s spread throughout the material. - **Convection** - when a gas or liquid moves from one place to another, such as when a gas or liquid moves from one place to another. - **Radiation** - Heat transfer when heat is given off in all directions around them (The sun and other hot objects radiates energy) ### Energy resources - **Fossil fuels:** - **Coal** - being mined formed from trees and other vegetation buried in swamps crated by the encroaching sea - **Petroleum** a liquid mixture of gaseous liquid and solid hydrocarbons. - **Natural Gas** - composed entirely of carbon and hydrogen. It is 50 to 94% methane and other hydrocarbons. - **Hydroelectric Power** - hydroelectric power pertains to the production of electricity by means of generators driven by water turbines. - **Geothermal Energy** - Thermal energy inside the earth, energy of steam from beneath the earth's surface - **Wind Energy**-energy harnessed through the windmill - **Solar Energy**- energy from the sun, radiant energy. The visible light is harnessed to produce the electricity by means of so-called solar cells or photovoltaic cells, which generate electricity when exposed to sunlight # Earth ## Formation of the Earth - In the beginning there is only a super-massive gaseous point in an empty universe - enough energy is created to break the gravitational bond holding this massive body together, exploding the super-heated particles throughout space - In less than one millionth of a second, protons, neutrons, electrons, and their antiparticles begin to form. - As time moves on, particles begin to cool by giving off energy, which allows them to combine to create the first and most simple ion, hydrogen, as well as a few more massive atoms. - More time passes; the atoms are becoming more abundant in the universe. They begin to pull together through atomic forces and the gravitational force. - Gaseous bodies become more massive, attracting more atoms and becoming more massive - The gravitational force of these early bodies is so great that they collapse in on themselves, beginning fusion. - Hydrogen atoms combine, yielding larger atoms and enormous amounts of energy; enough energy to keep these stars from collapsing. - Eventually, the fusion process has to end and the star will explode, sending out more massive atoms into the universe. - Over time, these atoms collect and combine to create planets, smaller stars, asteroids, and numerous other solid bodies. ## Formation of Solar System - As matter began to condense and stars began to form, one such star appeared where the Sun now appears within the Milky Way Galaxy. - After igniting with fusion and burning its usable hydrogen and other larger elements, the star exploded, sending matter out in all directions. - Once again, through gravitational forces, this matter eventually cooled and collected in a few key areas, forming the planets and the asteroid belt. - The asteroid belt is simply an early form of the collection of matter that was not able to completely form a planet - Some early planets may have collided with other early planets, creating larger planets, moons, or possibly space rocks. - A smaller star began to form at the center of the previous explosion and our Sun started its fusion process again. ## Earth's Structure - The earth consists of several layers. - The three main layers are the core, the mantle and the crust. - The core is the inner part of the earth, the crust is the outer part and between them is the mantle. - The earth is surrounded by the atmosphere. - It hasn't been possible to take a look inside the earth because the current technology doesn't allow it. ### THE CORE - The inner part of the earth is about 1,800 miles (2,900 km) below the earth's surface. - A dense ball of the elements iron and nickel. - Divided into two layers: the inner core and the outer core. - **Inner core** - The center of earth is solid and about 780 miles (1,250 km) thick. - **Outer core** - about 1370 miles (2,200 km) thick. The outer core spins around the inner core and that causes the earth's magnetism ### THE MANTLE - The layer above the core - Begins about 6 miles (10 km) below the oceanic crust and about 19 miles (30 km) below the continental crust. - About 1,800 miles (2,900 km) thick and makes up nearly 80 percent of the Earth's total volume. - To divide into the inner mantle and the outer mantle. ### THE CRUST - Lies above the mantle and is the earth's hard outer shell, the surface on which we are living. - Much thinner than the other layers. - It floats upon the softer, denser mantle. - Made up of solid material but not everywhere the same. - **Oceanic crust:** about 4-7 miles (6-11 km) thick and consists of heavy rocks, like basalt. - **Continental crust** : about 19 miles (30 km) thick. It is mainly made up of light material, like granite. ## Plate Tectonics - The earth's crust consists of a number of moving pieces or plates that are always colliding or pulling apart. - The Lithosphere consists of nine large plates and twelve smaller ones. - The continents are imbedded in continental plates; the oceanic plates make up much of the sea floor. - The study of Tectonic plates - called plate tectonics - helps to explain continental drift, the spreading of the sea floor, volcanic eruptions and how mountains are formed. - The force that causes the movement of the tectonic plates may be the slow churning of the mantle beneath them. - Mantle rock is constantly moved upwards to the surface by the high temperatures below and then sinks by cooling. This cycle takes millions of years. ## Continental drift - The drift of the plates across the surface of the earth has been going on over millions of years. - Changes the outward appearance of the earth. - When you look at the map of the world, you see how well the east coast of North and South America fits into the west coast of Europe and Africa. - Over millions of years these continents have slowly drifted apart. ### Diverging plates - Where plates pull apart, hot molten rock (fluid magma) emerges as lava and so new matter is added to the plates. - In this way new oceanic plates are formed. - The place where this happens is known as a mid-ocean ridge. - Mid-ocean ridges are rarely more than about 4,920 ft. (1,500 m) high - May snake along the ocean bed for thousands of miles. - Beneath each of the world's great oceans there is a mid-ocean ridge. - An example is the Mid-Atlantic Ridge in the Atlantic Ocean, which stretches from the North Pole to the South Pole. - Mid-ocean ridges are areas of much volcanic and earthquake activity ### Converging plates: - In many places the huge plates of the earth's surface are slowly moving together with unimaginable force. - Sometimes the edge of one plate is gradually destroyed by the force of collision, sometimes the impact simply crimps the plates' edges, thereby creating great mountain ranges. - **Subduction:** when one tectonic plate bends beneath the other. - Usually happens because a dense oceanic plate collides with a lighter continental plate - You can see this along the Pacific coast of South-America. The oceanic plate dips beneath into the Asthenosphere. - Through the heat of the Asthenosphere, the subducted plate melts. At the surface an ocean trench is created, followed by an arc of islands. - In this area also volcanic activities and earthquakes occur. ### Seafloor Spreading - Studies show that volcanic activity under the sea causes magma from beneath the earth's crust to rise to the surface, forming a very long ridge along the middle of the oceans that separate the large continents. ## Diastrophism - - the process which involves movements of the earth's crust such that a portion is pushed up, push down or forced sideways - **Folding:** the process when the sideward forces acting on rocks deform the rocks into wavelike folds after tilting, bending of wrinkling. - **Faulting:** sliding or moving over of rock layers over one another along the break or fracture, may occur vertically or horizontally. ## Volcanoes - A Volcano is a gap in the earth where molten rock and other materials come to the earth's surface. - Some volcanoes are just cracks in the earth's crusts. - Others are weak places in the earth's crust. - magma bubbles up through the crust and comes to the earth's surface. - Magma is molten rock - occurs by partial melting of the crust and the mantle by high temperatures deep down in the ground. - Once magma comes to the earth's surface it is called lava. ### Active and Non-Active Volcanoes - **Active volcanoes:** which are likely to erupt at any moment - **Dormant volcanoes** : which lie dormant for centuries, but then erupt suddenly and violently - **Extinct volcanoes:** ones no longer likely to erupt ### Types of volcanoes - **The shield volcano:** - This is a broad, shallow volcanic cone, which arises because the running lava, which is fluid and hot, cools slowly. - **The dome volcano:** - This one has a steep, convex slope from thick, fast-cooling lava - **The ash-cinder volcano:** - Throws out - besides lava - much ash into the air. - Through this, the volcanic cone is built up from alternate layers of ash and cinder. - **The composite volcano:** - These are also built up from alternate layers of lava and ash - It has many little craters on its slope. - **The caldera volcano:** - An older volcano with a large crater which can be 62 miles(100km) wide. - In this crater many little new craters are formed. ## Earthquakes - An Earthquake is in fact the shaking of the ground caused by sudden movements in the earth's crust. - The biggest earthquakes are set off by the movement of tectonic plates. Some plates slide past each other gently, but others can cause a heavy pressure on the rocks, so they finally crack and slide past each other. - Vibrations or shock waves are caused, which go through the ground. It is these vibrations or seismic waves which cause an earthquake. - The closer to the source of the earthquake (the focus or hypocenter), the more damage occurs. - Earthquakes are classified according to the depth of the focus. | Depth | Classification | | :------ | :------------------- | | 0-43 miles (0-70 km) below ground: | shallow earthquakes | | 43-186 miles (70-300 km) below ground: | intermediate earthquakes | | deeper than 186 miles (300 km) below ground: | deep earthquakes | - Big earthquakes begin with light vibrations (foreshocks). These are the initial fractures in the rocks. - After the main shock, there may be minor aftershocks, most of the time for months. This occurs as the rocks settle down. ## Rocks - Rocks are classified in three types based on how they are formed. - **Igneous rocks** are formed when molten rock (magma) from within Earth cools and solidifies. - **Intrusive igneous rocks** solidify beneath Earth's surface - **Extrusive igneous rocks** solidify at the surface. - Examples: Granite, basalt, obsidian - **Sedimentary rocks** are formed when sediment (bits of rock plus material such as shells and sand) gets packed together. - Can take millions of years to form. - Most rocks that you see on the ground are sedimentary - Examples: Limestone, sandstone, shale - **Metamorphic rocks** are sedimentary or igneous rocks that have been transformed by heat, pressure or both. - Usually formed deep within Earth, during a process such as mountain building - Examples: Schist, marble, slate ## The Rock Cycle - The three major types of rocks, igneous, sedimentary, and metamorphic rocks are interrelated by a series of natural processes. - **Igneous rocks** form from the cooling and crystallization of hot molten lava and magma. - **Igneous rocks** undergo weathering and erosion to form sediments. - **Sediments** are deposited and lithified by compaction and cementation to form sedimentary rocks. - **Sedimentary rock** become buried by additional sedimentary deposition, and when they are deep within the Earth, they are subjected to heat and pressure which causes them to become metamorphic rocks. - **Metamorphic rocks** begin to melt. - **Partially molten metamorphic rocks** are known as migmatite. - As melting proceeds with increasing temperatures and depths of burial, eventually the rock becomes molten and becomes magma - cools and crystallizes to form plutonic igneous rock, or which is erupted onto the Earth's surface as lava, and cools and crystallizes to form volcanic igneous rock. ### Weathering - Breaking down of rocks brought about by either physical or chemical means giving rise to sediments or ther rock fragments #### Types of Weathering ##### Physical or mechanical weathering - **Frost wedging** - water expands when it freezes - **Exfoliation or unloading** - - rock breaks off into leaves or sheets along joints which parallel the ground surface; - caused by expansion of rock due to uplift and erosion; removal of pressure of deep burial; - **Thermal expansion** - - repeated daily heating and cooling of rock - heat causes expansion; cooling causes contraction. - different minerals expand and contract at different rates causing stresses along mineral boundaries. ##### Chemical weathering - Rock reacts with water, gases and solutions (may be acidic); will add or remove elements from minerals. ###### Dissolution (or solution) - - Several common minerals dissolve in water. - Halite - Calcite - Limestone and marble contain calcite and are soluble in acidic water - Caves and caverns typically form in limestone - speleothems are cave formations - speleothems are made of calcite - form a rock called travertine - stalactites - hang from ceiling - stalagmites - on the ground - Karst topography forms on limestone terrain and is characterized by: - caves/caverns, - sinkholes, - disappearing streams, - springs ###### Oxidation - Oxygen combines with iron-bearing silicate minerals causing "rusting" - Iron oxides are produced. Iron oxides are red, orange, or brown in color - Mafic rocks such as basalt (which may contain olivine, pyroxene, or amphibole) weather by oxidation to an orange color - "Georgia Red Clay" derives its color from the oxidation of iron bearing minerals ###### Hydrolysis ###### Biological weathering - Organisms can assist in breaking down rock into sediment or soil. - Roots of trees and other plants - Lichens, fungi, and other micro-organisms - Animals (including humans) - **Erosion:** the process by which rock fragments and sediments are carried along by such agents as wind and running water - **Deposition:** the process by which rock fragments and sediments ae carried by agents of erosion are dropped or deposited in other places. - **Compacting:** the process by which rock fragments and other materials that accumulated, usually at the bottom of a thick column of water, get cemented together and harden into rock - **Metamorphism** - a change in constitution of a rock brought about by pressure, heat and chemical action resulting in a more compact and highly crystalline condition of the rock. - **Melting** - **Cooling and Solidifying** ## Minerals and Gems - Minerals are solid, inorganic (not living) substances that are found in and on earth. - Most are chemical compounds, which means they are made up of two or more elements. - For example, the mineral sapphire is made up of aluminum and oxygen. - A few minerals, such as gold, silver and copper, are made from a single element. - Minerals are considered the building blocks of rocks. Rocks can be a combination of as many as six minerals. - Many minerals, such as gold and silver, are very valuable because they are beautiful and rare. - Limestone, clay and quartz are other examples of minerals. - Gems are minerals or pearls that have been cut and polished. - They are used as ornaments, such as jewelry. - Precious stones are the most valuable gems. - They include diamonds, rubies and emeralds ## Atmosphere - The earth is surrounded by all kind of gases. - This layer is called the earth's Atmosphere - Without this atmosphere life on earth isn't possible. - It gives us air, water, heat, and protects us against harmful rays of the sun and against meteorites. - This layer around the earth is a colorless, odorless, tasteless 'sea' of gases, water and fine dust. - The atmosphere is made up of different layers with different qualities. - It consists of 78 percent nitrogen, 21 percent oxygen, 0.93 percent argon, 0.03 percent carbon dioxide and 0.04 percent of other gases.. - The Troposphere is the layer where the weather happens. - Above this layer is the Stratosphere and in between them is the Ozone layer, that absorbs the sun's harmful ultraviolet rays. - Above the Stratosphere is the Mesosphere, the Thermosphere including the Ionosphere - and the Exosphere. - The atmosphere measures about 500 miles (800km). ### Layers of the Atmosphere - **The Troposphere** - The lowest layer of the atmosphere and measures about 7 miles(12 km) - It contains over 75 percent of all the atmosphere's gases and vast quantities of water and dust. - The sun heats the ground, it keeps this thick mixture churning. - The weather is caused by these churnings of the mass. - Normally warmest at ground level and cools higher up - where it reaches its upper boundary (the tropopause). - The tropopause varies in height. - At the equator it is at 11.2 miles (8 km) high, at 50 N and 50 S, 5.6 miles(9 km) and at the poles 3.7 miles(6 km) high. - **Stratosphere** - Extends from the tropopause up to its boundary (the Stratopause), 31 miles (50 km) above the Earth's surface. - It contains 19 percent of the atmosphere's gases - Contains little water vapour. Movements of the gases are slow. - Contains the ozone layer, a band of ozone gas, that absorbs harmful ultraviolet rays of the sun. - The higher you get in the atmosphere, the warmer the air gets. - The temperature rises from -76 °F(-60 °C) at the bottom to a maximum of about 5 °F (10°C) at the stratopause. - **Mesosphere** - The next layer above the stratopause and extends to its upper boundary (the Mesopause), at 50 miles(80 km) above the ground. - The gases in the mesosphere are too thin to absorb much of the sun's heat. - The air is still thick enough to slow down meteorites hurtling into the atmosphere. - They burn up, leaving fiery trails in the night sky. - The temperatures in the mesosphere drop to -184 °F(-120 °C) at the mesopause. - **Thermosphere** - The layer above the mesopause. - The gases of the thermosphere are even thinner than those in the mesosphere, but they absorb ultraviolet light from the sun. - The temperatures rise to 3,600 °F (2,000 °C) at the top. - At a height of 430 miles (700 km) of the earth's surface. - Contains the Ionosphere. - Extends of 62 miles(100 km) to 190 miles(300 km) of the earth's surface. - **Ionosphere** - Part of the thermosphere. - Made of electrically charged gas particles (ionised). - The particles get this electric charge by ultraviolet rays of the sun. - Has the important quality of bouncing radio signals, transmitted from the earth. - That's why places all over the world can be reached via radio. - **Exosphere** - The outermost layer of the atmosphere and extends from 430 miles (700 km) to 500 miles (800 km) above the ground. - The gases get thinner and thinner and drift off into space. ## Air - The atmosphere is of vital importance for life on earth. - Without atmosphere life would be impossible. - It gives us air to breathe and protects us from meteorites and ultraviolet rays from the sun. - The atmosphere absorbs so much heat that temperatures on earth are such that life is possible. - The weather that exists by constant circulation of water to water vapor, to rain to water. - This cycle causes, together with the differences in temperature and circulation of air (wind), erosion of the earth's surface. - By erosion, the outside of the earth changes through the years. ### Air movement - Warm air is less dense than cold air. - Thus, warm air rises above cold air making the pressure below lower. - The horizontal movement of air from high pressure area to lower pressure area produces wind. ### Sea breezes and land breezes - When spending a day at the beach, a noticeable drop in temperature may occur during the early afternoon as a cool breeze begins to blow off of the water. - This wind is known as the "sea breeze", which occurs in response to differences in temperature between a body of water and neighboring land. - Sea-breeze circulations most often occur on warm sunny days during the spring and summer when the temperature of the land is normally higher than the temperature of the water. - During the early morning hours, the land and the water start out at roughly the same temperature - On a calm morning, a given pressure surface will be at the same height above both the land and water - A few hours later, the sun's energy begins to warm the land more rapidly than the water. - By later in the day, the temperatures of the land increases while the temperature of the water remains relatively constant. - This occurs because water, especially large bodies of water like a lake or ocean, are able to absorb more energy than land without warming. - It is important to remember that the air is not heated directly from above by the sun - Instead, most of the incoming solar energy actually passes right through the atmosphere. - However, as the land absorbs this energy, heat is radiated back into the atmosphere (from the earth), warming the overlying air. - Some of this heat is transported to higher levels in the atmosphere through convection. - On the other hand, since the temperature of the water remains relatively constant throughout the day, the air over the water is not heated from below (as over land. - Resulting in lower air temperatures over the water. - On clear, calm evenings, temperature differences between a body of water and neighboring land produce a cool wind that blows offshore. - This wind is called a "land breeze". - Land breezes are strongest along the immediate coastline but weaken considerably further inland. - Land-breeze circulations can occur at any time of year, but are most common during the fall and winter seasons when water temperatures are still fairly warm and nights are cool. ## Air Pollution - When large amount of dust, soot, bacteria, and other harmful gases get into the air it is being polluted. - The main sources of air pollution in the Philippines are: 1) industry and 2) transportation | Pollutant | Sources | Effects | | :----------------- | :----------------------- | :---------------------------------------------------------------------------------------------- | | Ozone | Not created directly, but is formed when nitrogen oxides and volatile organic compounds mix in sunlight | Ozone near the ground can cause a number of health problems. Ozone can lead to more frequent asthma attacks in people who have asthma and can cause sore throats, coughs, and breathing difficulty. It may even lead to premature death. Ozone can also hurt plants and crops. | | Carbon monoxide | When engines burn fossil fuels (emissions are higher when engines are not tuned properly, and when fuel is not completely burned) | Carbon monoxide makes it hard for body parts to get the oxygen they need to run correctly. Exposure to carbon monoxide makes people feel dizzy and tired and gives them headaches. Elderly people with heart disease are hospitalized more often when