One of the items of information given in the Qur'an about rain is that it is sent down to Earth in due measure. This is mentioned in Sura Zukhruf as follows;
"It is He who sends down water in due measure from the sky by which We bring a dead land back to life. That is how you too will be raised (from the dead)." (The Qur'an, 43:11)
This measured quantity in rain has again been discovered by modern research. It is estimated that in one second, approximately 16 million tons of water evaporates from the Earth. This figure amounts to 513 trillion tons of water in one year. This number is equal to the amount of rain that falls on the Earth in a year. This means that water continuously circulates in a balanced cycle, in a "measure". Life on Earth depends on this water cycle. Even if people used all the available technology in the world, they would not be able to reproduce this cycle artificially.
Even a minor deviation in this equilibrium would very soon give rise to a major ecological imbalance that would bring about the end of life on Earth. Yet, this never happens, and rain keeps falling every year in exactly the same quantity just as revealed in the Qur'an.
Every year, the amount of water that evaporates and that falls back to the Earth in the form of rain is "constant": 513 trillion tons. This constant amount is declared in the Qur'an by the expression "sending down water in due measure from the sky". The constancy of this quantity is very important for the continuity of the ecological balance, and therefore, life. |
The above illustration shows the water droplets being released into the air. This is the first stage in the formation of rain. After that, the water droplets in the newly formed clouds will be suspended in the air and then condense to form rain. All of these stages are related in the Qur'an. |
How rain forms remained a great mystery for a long time. Only after weather radar was invented was it possible to discover the stages by which rain is formed.
According to this, the formation of rain takes place in three stages. First, the "raw material" of rain rises up into the air with the wind. Later, clouds are formed, and finally raindrops appear.
The Qur'an's account of the formation of rain refers exactly to this process. In one verse, this formation is described in this way:
"It is God Who sends the winds which stir up clouds which He spreads about the sky however He wills. He forms them into dark clumps and you see the rain come pouring out from the middle of them. When He makes it fall on those of His slaves He wills, they rejoice" (The Qur'an, 30:48)
Now, let us examine these three stages outlined in the verse more technically.
First Stage: "It is God Who sends the winds..."
(A) Isolated small pieces of clouds (cumulus clouds) (B) When the small clouds join together, updrafts within the larger cloud increase, and so the cloud is stacked up. |
Countless air bubbles formed by the foaming of the oceans continuously burst and cause water particles to be ejected towards the sky. These particles, which are rich in salt, are then carried away by winds and rise upward in the atmosphere. These particles, which are called aerosols, function as water traps, and form cloud drops by collecting around the water vapour themselves, which rises from the seas as tiny droplets.
Second Stage: "...which stir up clouds which He spreads about the sky however He wills. He forms them into dark clumps..."
The clouds are formed from water vapour that condenses around the salt crystals or dust particles in the air. Because the water droplets in these clouds are very small (with a diameter between 0.01 and 0.02 mm), the clouds are suspended in the air, and spread across the sky. Thus, the sky is covered in clouds.
1. Ice Crystalss | 2. Water Drops |
These updrafts cause the cloud body to grow vertically, so the cloud is stacked up. This vertical growth causes the cloud body to stretch into cooler regions of the atmosphere, where drops of water and hail formulate and begin to grow larger and larger. When these drops of water and hail become too heavy for the updrafts to support them, they begin to fall from the cloud as rain, hail, etc. This scientific fact was announced in verse 43 of Sura Nur fourteen centuries ago by God in this way: "...then (He) makes them into a stack, and then you see the rain come out of …" |
Third Stage: "...and you see the rain come pouring our from the middle of them"
The water particles that surround salt crystals and dust particles thicken and form raindrops, so, drops that become heavier than the air leave the clouds and start to fall to the ground as rain.
As we have seen, every stage in the formation of rain is related in the verses of the Qur'an. Furthermore, these stages are explained in exactly the right sequence. Just as with many other natural phenomena on the Earth, God gives the most correct explanation of this phenomenon as well, and made it known to people in the Qur'an centuries before it was discovered.
In another verse, the following information is given about the formation of rain:
"Have you not seen how God drives along the clouds, then joins them together, then makes them into a stack, and then you see the rain come out of it? And He sends down from the sky mountain masses (of clouds) with cold hail in them, striking with it anyone He wills and averting it from anyone He wills. The brightness of His lightning almost blinds the sight." (The Qur'an, 24:43)
Scientists studying cloud types came across surprising results regarding the formation of rain clouds. Rain clouds are formed and shaped according to definite systems and stages. The formation stages of cumulonimbus, one kind of rain cloud, are these:
Small clouds (cumulus clouds) are carried along and joined together by the wind, that is, as the verse says: "ÉGod drives along the clouds, then joins them together…" |
Stage, Being driven along: Clouds are carried along, that is, they are driven along, by the wind.
Stage, Joining: Then, small clouds (cumulus clouds) driven along by the wind join together, forming a larger cloud.9
Stage, Stacking: When the small clouds join together, updrafts within the larger cloud increase. The updrafts near the centre of the cloud are stronger than those near the edges. These updrafts cause the cloud body to grow vertically, so the cloud is stacked up. This vertical growth causes the cloud body to stretch into cooler regions of the atmosphere, where drops of water and hail formulate and begin to grow larger and larger. When these drops of water and hail become too heavy for the updrafts to support them, they begin to fall from the cloud as rain, hail, etc.10
We must remember that meteorologists have only recently come to know these details of cloud formation, structure and function, by using advanced equipment like planes, satellites, computers etc. It is evident that God has given us a piece of information that could not have been known 1,400 years ago.
In one verse of the Qur'an, the "fecundating" characteristic of the winds, and the formation of rain as a result are mentioned.
"And We send the fecundating winds, then cause water to descend from the sky, therewith providing you with water in abundance." (The Qur'an, 15:22)
In this verse, it is pointed out that the first stage in the formation of rain is wind. Until the beginning of the 20th century, the only relationship between the wind and the rain that was known, was that the wind drove the clouds. However, modern meteorological findings have demonstrated the "fecundating" role of the wind in the formation of rain.
The picture above shows the stages in the formation of a wave. Waves are formed by the wind blowing above the surface of the water. With the wind, water particles start to move in a circular motion. This movement soon forms waves, one after the other, and bubbles formed by the waves spread in the air. This is the first stage in the formation of rain. This process is declared in the verse as "We send the fecundating winds and then cause water to descend from the sky." |
This fecundating function of the wind works in the following way:
On the surface of oceans and seas, countless air bubbles form because of the water's foaming action. The moment these bubbles burst, thousands of tiny particles, with a diameter of just one hundredth of a millimeter, are thrown up into the air. These particles, known as "aerosols", mix with dust carried from the land by the wind, and are carried to the upper layers of the atmosphere. These particles carried to higher altitudes by winds come into contact with water vapour up there. Water vapour condenses around these particles and turns into water droplets. These water droplets first come together and form clouds, and then fall to the Earth in the form of rain.
As seen, winds "fecundate" the water vapour floating in the air with the particles they carry from the sea, and eventually help the formation of rain clouds.
If winds did not possess this property, water droplets in the upper atmosphere would never form, and there would be no such thing as rain.
The most important point here is that this critical role of the wind in the formation of rain was stated centuries ago in a verse of the Qur'an, at a time when people knew very little about natural phenomena…
One of the properties of seas that has only recently been discovered is related in a verse of the Qur'an as follows:
"He has let loose the two seas, converging together, with a barrier between them they do not break through." (The Qur'an, 55:19-20)
A. Depths (metres) | 3. Atlantic Ocean Water Salinity lower than 0.36 % | 5. Salinity higher than 0.365 % |
There are large waves, strong currents, and tides in the Mediterranean Sea and the Atlantic Ocean. Mediterranean Sea water enters the Atlantic by Gibraltar. But their temperature, salinity, and densities do not change, because of the barrier that separates them. |
This property of the seas, that they come together yet do not mingle with one another at all, has only very recently been discovered by oceanographers. Because of the physical force called "surface tension", the waters of neighboring seas do not mix. Caused by the difference in the density of their waters, surface tension prevents them from mingling with one another, just as if a thin wall were between them.11
The interesting side to this is that during a period when people had no knowledge of physics, surface tension, or oceanography; this was revealed in the Qur'an.
A satellite photograph of Gibraltar |
"Or (the unbelievers' state) are like the darkness of a fathomless sea which is covered by waves above which are waves above which are clouds, layers of darkness, one upon the other. If he puts out his hand, he can scarcely see it. Those God gives no light to, they have no light." (The Qur'an, 24:40)
The general environment in deep seas is described in the book named Oceans:
The darkness in deep seas and oceans is found around a depth of 200 meters and below. At this depth, there is almost no light. Below a depth of 1000 meters there is no light at all.12
Measurements made with today's technology have revealed that between 3 and 30 percent of the sunlight is reflected at the surface of the sea. Then, almost all of the seven colours of the light spectrum are absorbed, one after another, in the first 200 meters, except for blue light (picture at left). Below a depth of 1,000 meters, there is no light at all. (above picture). This scientific fact was pointed out in the verse 40 of Sura Nur in the Qur'an 1,400 years ago. |
Today, we know about the general structure of the sea, the characteristics of the living things in it, its salinity, as well as the amount of water it contains, its surface area and depth. Submarines and special equipment, developed with modern technology, enable scientists to obtain this information.
Human beings are not able to dive more than 40 meters down without the aid of special equipment. They cannot survive unaided in the deep, dark parts of the oceans, such as at a depth of 200 meters. For these reasons, scientists have only recently been able to discover these detailed pieces of information about seas. However, the statement of "darkness in a deep sea" was used in Sura Nur 1,400 years ago. It is certainly one of the miracles of the Qur'an that such information was given at a time where no equipment to enable man to dive into the depths of the oceans was available.
1. Surface Waves | 3. Less Dense Water |
The picture to the left represents internal waves at interface between two layers of water of different densities. The lower layer is denser then the upper one. This scientific fact, declared in verse 40 of Sura Nur of the Qur'an 14 centuries ago, has been discovered by today's scientists only very recently. |
In addition, the statement in verse 40 of Sura Nur "...like the darkness of a fathomless sea which is covered by waves above which are waves above which are clouds..." draws our attention to another miracle of the Qur'an.
Scientists have recently discovered that there are internal waves, which "occur on density interfaces between layers of different densities." These internal waves cover the deep waters of seas and oceans because deep water has a higher density than the water above it. Internal waves act like surface waves. They can break, just like surface waves. Internal waves cannot be seen by the human eye, but they can be detected by studying temperature or salinity changes at a given location.13
The statements in the Qur'an run absolutely parallel to the above explanation. Without research, one can only see the waves on the surface of the sea. It is impossible for one to know about the internal waves beneath the sea. Yet, in Sura Nur, God draws our attention to another type of wave that occurs in the depths of the oceans. Certainly, this fact, which scientists has discovered very recently, shows once again that the Qur'an is the word of God.
1. Prefrontal Area |
"No indeed! If he does not stop, We will grab him by the forelock, a lying, sinful forelock." (The Qur'an, 96:15-16)
The expression "the lying, sinful forelock" in the above verse is most interesting. Research carried out in recent years revealed that the prefrontal area, which is responsible for the management of particular functions of the brain, lies in the frontal part of the skull. Scientists only discovered the functions of this area, which the Qur'an pointed out 1,400 years ago, in the last 60 years. If we look inside the skull at the front of the head, we will find the frontal area of the cerebrum. A book entitled Essentials of Anatomy and Physiology, which includes the results of the latest research on the functions of this area, says:
The motivation and the foresight to plan and initiate movements occur in the anterior portion of the frontal lobes, the prefrontal area. This is a region of association cortex…14
The book also says:
In relation to its involvement in motivation, the prefrontal area is also thought to be the functional center for aggression…15
So, this area of the cerebrum is responsible for planning, motivation, and initiating good and sinful behaviour, and is responsible for telling lies and the truth.
It is clear that the statement "the lying, sinful forelock" corresponds completely to the above explanations. This fact, which scientists have only discovered in the last 60 years, was stated by God in the Qur'an long years ago.
Many diverse subjects are mentioned in the Qur'an in the course of inviting people to believe. Sometimes the heavens, sometimes animals, and sometimes plants are shown as evidence to man by God. In many of the verses, people are called upon to turn their attention to their own creation. They are often reminded how man came into the world, which stages he has passed through, and what his essence is:
"It is We Who have created you. Why, then, do you not accept the truth? Have you ever considered that (seed) which you emit? Is it you who create it? Or are We the Creator?" (The Qur'an, 56:57-59)
The creation of man, and the miraculous aspect of this, is stressed in many other verses. Some items of information within these verses are so detailed that it is impossible for anyone living in the 7th century to have known them. Some of these are as follows:
People living when the Qur'an was revealed, to be sure, knew that the basic substance of birth was related to the semen of the male emitted during sexual intercourse. And the fact that the baby was born after a nine-month period was obviously an observable event not calling for any further investigation. However, the items of information just quoted were far above the level of learning of the people living at that time. These were verified by 20th century science.
Now, let us go over them one by one.
During sexual intercourse, 250 million sperms are emitted from the male at a time. The sperms undertake an arduous journey in the mother's body until they make it to the ovum. Only a thousand out of 250 million sperms succeed in reaching the ovum. At the end of this five-minute race, the ovum, half the size of a grain of salt, will let only one of the sperms in. That is, the essence of man is not the whole semen, but only a small part of it. This is explained in the Qur'an:
"Does man reckon he will be left uncontrolled (without purpose)? Was he not once a drop of ejected semen?" (The Qur'an, 75:36-37)
In the picture to the left, we see semen ejected into the uterus. Only very few sperms out of 250 million sperms emitted from the male can make it to the ovum. The sperm that will fertilise the egg is the only one out of a thousand sperms that have managed to survive. The fact that man is made not from the entire semen, but only a small part of it, is related in the Qur'an with the expression, "a drop of ejected semen". |
As we have seen, the Qur'an informs us that man is made not from the entire semen, but only a small part of it. That the particular emphasis in this statement announces a fact only discovered by modern science is evidence that the statement is divine in origin.
In the Qur'an, it is said that masculinity or femininity are created out of "a drop of semen which has been ejected". However, until fairly recently, it was believed that a baby's sex was determined by the mother's cells. Science only discovered this information given in the Qur'an in the 20th century. This and many other similar details about the creation of man were stated in the Qur'an centuries ago. |
The fluid called semen, which contains the sperms, does not consist of sperms alone. On the contrary, it is made up of a mixture of different fluids. These fluids have different functions, such as containing the sugar necessary for providing energy for the sperms, neutralising the acids at the entrance of the uterus, and creating a slippery environment for the easy movement of the sperms.
Interestingly enough, when semen is mentioned in the Qur'an, this fact, which was discovered by modern science, is also referred to, and semen is defined as a mixed fluid:
"We created man from a mingled drop to test him, and We made him hearing and seeing." (The Qur'an, 76:2)
In another verse, semen is again referred to as a mixture, and it is stressed that man is created from the "extract" of this mixture:
"He who has created all things in the best possible way. He commenced the creation of man from clay; then He made his progeny from an extract of discarded fluid." (The Qur'an, 32:7-8)
The Arabic word "sulala", translated as "extract", means the essential or best part of something. By either implication, it means "part of a whole". This shows that the Qur'an is the word of a Will that knows the creation of man down to its slightest detail. This Will is God, the Creator of man.
The Y chromosome carries characteristics of masculinity, while the X chromosome carries those of femininity. In the mother's egg, there is only the X chromosome, which determines female characteristics. In the semen from the father, there are sperms that includes either X or Y chromosomes. Therefore, the sex of the baby depends on whether the sperm fertilising the egg contains an X or Y chromosome. In other words, as stated in the verse, the factor determining the sex of the baby is the semen, which comes from the father. This knowledge, which could not have been known at the time when the Qur'an was revealed, is evidence to the fact that the Qur'an is the word of God. |
Until fairly recently, it was thought that a baby's sex was determined by the mother's cells. Or at least, it was believed that the sex was determined by the male and female cells together. But we are given different information in the Qur'an, where it is stated that masculinity or femininity is created out of "a drop of sperm which has been ejected".
"He has created both sexes, male and female from a drop of semen which has been ejected." (The Qur'an, 53:45-46)
The developing disciplines of genetics and molecular biology have scientifically validated the accuracy of this information given by the Qur'an. It is now understood that sex is determined by the sperm cells from the male, and that the female has no role in this process.
Chromosomes are the main elements in determining sex. Two of the 46 chromosomes that determine the structure of a human being are identified as the sex chromosomes. These two chromosomes are called "XY" in males, and "XX" in females, because the shapes of the chromosomes resemble these letters. The Y chromosome carries the genes that code for masculinity, while the X chromosome carries the genes that code for femininity.
The formation of a new human being begins with the cross combination of one of these chromosomes, which exist in males and females in pairs. In females, both components of the sex cell, which divides into two during ovulation, carry X chromosomes. The sex cell of a male, on the other hand, produces two different kinds of sperm, one that contains X chromosomes and the other Y chromosomes. If an X chromosome from the female unites with a sperm that contains an X chromosome, then the baby is female. If it unites with the sperm that contains a Y chromosome, the baby is male.
In the Qur'an, it is said that masculinity or femininity are created out of "a drop of semen which has been ejected". However, until fairly recently, it was believed that a baby's sex was determined by the mother's cells. Science only discovered this information given in the Qur'an in the 20th century. This and many other similar details about the creation of man were stated in the Qur'an centuries ago. |
In other words, a baby's sex is determined by which chromosome from the male unites with the female's ovum.
None of this was known until the discovery of genetics in the 20th century. Indeed, in many cultures, it was believed that a baby's sex was determined by the female's body. That was why women were blamed when they gave birth to girls.
Thirteen centuries before human genes were discovered, however, the Qur'an revealed information that denies this superstition, and referred to the origin of sex lying not with women, but with the semen coming from men.
In the first phase of its development, the baby in the mother's womb is in the form of a zygote, which clings to the uterus in order to take nourishment from the mother's blood. In the picture above is a zygote, which looks like a piece of flesh. This formation, which has been discovered by modern embryology, was miraculously stated in the Qur'an 14 centuries ago with the word "alaq", which means "a thing that clings to some place" and is used to describe leeches that cling to a body to suck blood. |
If we keep on examining the facts announced to us in the Qur'an about the formation of human beings, we again encounter some very important scientific miracles.
When the sperm of the male unites with the ovum of the female, the essence of the baby to be born is formed. This single cell, known as a "zygote" in biology, will instantly start to reproduce by dividing, and eventually become a "piece of flesh" called an embryo. This of course can only be seen by human beings with the aid of a microscope.
The embryo, however, does not spend its developmental period in a void. It clings to the uterus just like roots that are firmly fixed to the earth by their tendrils. Through this bond, the embryo can obtain the substances essential to its development from the mother's body.16
Here, at this point, a very significant miracle of the Qur'an is revealed. While referring to the embryo developing in the mother's womb, God uses the word "alaq" in the Qur'an:
"Recite: In the name of your Lord Who created man from alaq. Recite: And your Lord is the Most Generous." (The Qur'an, 96:1-3)
The meaning of the word "alaq" in Arabic is "a thing that clings to some place". The word is literally used to describe leeches that cling to a body to suck blood.
Certainly, the use of such an appropriate word for the embryo developing in the mother's womb, proves once again that the Qur'an is a revelation from God, the Lord of all the Worlds.
The bones of the baby completing its development in the mother's womb are clothed with flesh during one particular stage. |
Another important aspect of the information given in the verses of the Qur'an is the developmental stages of a human being in the mother's womb. It is stated in the verses that in the mother's womb, the bones develop first, and then the muscles form which wrap around them.
"(We) then formed the drop into a clot and formed the clot into a lump and formed the lump into bones and clothed the bones in flesh; and then brought him into being as another creature. Blessed be God, the Best of Creators!" (The Qur'an, 23:14)
Embryology is the branch of science that studies the development of the embryo in the mother's womb. Until very recently, embryologists assumed that the bones and muscles in an embryo developed at the same time. For this reason, for a long time, some people claimed that these verses conflicted with science. Yet, advanced microscopic research conducted by virtue of new technological developments has revealed that the revelation of the Qur'an is word for word correct.
These observations at the microscopic level showed that the development inside the mother's womb takes place in just the way it is described in the verses. First, the cartilage tissue of the embryo ossifies. Then muscular cells that are selected from amongst the tissue around the bones come together and wrap around the bones.
This event is described in a scientific publication titled Developing Human in the following words:
During the seventh week, the skeleton begins to spread throughout the body and the bones take their familiar shapes. At the end of the seventh week and during the eighth week the muscles take their positions around the bone forms.17
In short, man's developmental stages as described in the Qur'an are in perfect harmony with the findings of modern embryology.
Many stages of a baby's development in the mother's womb are related in the Qur'an. As described in verse 14 of Sura Muminun, the cartilage of the embryo in the mother's womb ossifies first. Then these bones are covered with muscle cells. God describes this development with the verse: "…(We then) formed the lump into bones and clothed the bones in flesh" |
In the Qur'an, it is related that man is created in a three-stage process in the mother's womb.
"... He creates you stage by stage in your mothers' wombs in a threefold darkness. That is God, your Lord. Sovereignty is His. There is no god but Him. So what has made you deviate?" (The Qur'an, 39:6)
In the verse 6 of Sura Zumar, it is pointed out that man is created in the mother's womb in three distinct stages. Indeed, modern embryology has revealed that the baby's embryological development takes place in three distinct regions in the mother's womb. |
As will be understood, it is pointed out in this verse that a human being is created in the mother's womb in three distinct stages. Indeed, modern biology has revealed that the baby's embryological development takes place in three distinct regions in the mother's womb. Today, in all the embryology textbooks studied in faculties of medicine, this subject is taken as an element of basic knowledge. For instance in Basic Human Embryology, a fundamental reference text in the field of embryology, this fact is stated as follows:
"The life in the uterus has three stages: pre-embryonic; first two and a half weeks, embryonic; until the end of the eight week, and fetal; from the eight week to labor."18
These phases refer to the different developmental stages of a baby. In brief, the main characteristics of these developmental stages are as follows:
In this first phase, the zygote grows by division, and when it becomes a cell cluster, it buries itself in the wall of the uterus. While they continue growing, the cells organise themselves in three layers.
The second phase lasts for five and a half weeks, during which the baby is called an "embryo". In this stage, the basic organs and systems of the body start to appear from the cell layers.
From this stage on, the embryo is called a "foetus". This phase begins at the eighth week of gestation and lasts until the moment of birth. The distinctive characteristic of this stage is that the foetus looks just like a human being, with its face, hands and feet. Although it is only 3 cm. long initially, all of its organs have become apparent. This phase lasts for about 30 weeks, and development continues until the week of delivery.
Information on the development in the mother's womb became available only after observations with modern devices. Yet, just like many other scientific facts, these pieces of information are imparted in the verses of the Qur'an in a miraculous way. The fact that such detailed and accurate information was given in the Qur'an at a time when people had scarce information on medical matters is clear evidence that the Qur'an is not the word of man, but the word of God.
Mother's milk is an unmatched mixture that is created by God as both an excellent food-source for the newborn baby, and a substance that increases its resistance to diseases. Even artificial baby food produced by today's technology cannot substitute for this miraculous source of nutrition.
Every day, a new benefit of mother's milk to the baby is discovered. One of the facts that science has discovered about mother's milk is that suckling up to two years after birth is very beneficial.19 God gives us this important information, which was discovered by science only very recently, with the verse "…his weaning was in two years.." 14 centuries ago.
"And We have enjoined upon man goodness towards his parents: his mother bore him by bearing strain upon strain, and his weaning was in two years: (hence, O man,) be grateful to Me and to your parents; to Me is the eventual coming." (The Qur'an, 31:14)
Everyone, including identical twins, has a unique fingerprint. In other words, people's identities are coded at their fingertips. This coding system may also be compared to the barcode system that is used today. |
While it is stated in the Qur'an that it is easy for God to bring man back to life after death, peoples' fingerprints are particularly emphasized:
"Yes, We are able to put together in perfect order the very tips of his fingers." (The Qur'an, 75:3-4)
The emphasis on fingerprints has a very special meaning. This is because everyone's fingerprint is unique to himself. Every person who is alive or who has ever lived in this world has a set of unique fingerprints.
That is why fingerprints are accepted as a very important proof of identity, exclusive to their owner, and are used for this purpose around the world.
But what is important is that this feature of fingerprints was only discovered in the late 19th century. Before then, people regarded fingerprints as ordinary curves without any specific importance or meaning. However in the Qur'an, God points to the fingertips, which did not attract anyone's attention at that time, and calls our attention to their importance–an importance that was only finally understood in our day.
9.Anthes, Richard A., John J. Cahir, Alistair B. Fraser, and Hans A. Panofsky, 1981, The Atmosphere, 3. edition, Columbus, Charles E. Merrill Publishing Company, p. 268-269; Millers, Albert; and Jack C. Thompson, 1975, Elements of Meteorology, 2. edition, Columbus, Charles E. Merrill Publishing Company, p. 141
10.Anthes, Richard A.; John J. Cahir; Alistair B. Fraser; and Hans A. Panofsky, 1981, The Atmosphere, p. 269; Millers, Albert; and Jack C. Thompson, 1975, Elements of Meteorology, p. 141-142
11.Davis, Richard A., Jr. 1972, Principles of Oceanography, Don Mills, Ontario, Addison-Wesley Publishing, p. 92-93
12.Elder, Danny; and John Pernetta, 1991, Oceans, London, Mitchell Beazley Publishers, p. 27
13.Gross, M. Grant; 1993, Oceanography, a View of Earth, 6. edition, Englewood Cliffs, Prentice-Hall Inc., p. 205
14.Seeley, Rod R.; Trent D. Stephens; and Philip Tate, 1996, Essentials of Anatomy & Physiology, 2. edition, St. Louis, Mosby-Year Book Inc., p. 211; Noback, Charles R.; N. L. Strominger; and R. J. Demarest, 1991, The Human Nervous System, Introduction and Review, 4. edition, Philadelphia, Lea & Febiger , p. 410-411
15.Seeley, Rod R.; Trent D. Stephens; and Philip Tate, 1996, Essentials of Anatomy & Physiology, 2. edition, St. Louis, Mosby-Year Book Inc., p. 211
16.Moore, Keith L., E. Marshall Johnson, T. V. N. Persaud, Gerald C. Goeringer, Abdul-Majeed A. Zindani, and Mustafa A. Ahmed, 1992, Human Development as Described in the Qur'an and Sunnah, Makkah, Commission on Scientific Signs of the Qur'an and Sunnah, p. 36
17.Moore, Developing Human, 6. edition,1998.
18.Williams P., Basic Human Embryology, 3. edition, 1984, p. 64.
19.Rex D. Russell, Design in Infant Nutrition, http:// www. icr.org/pubs/imp-259.htm