# data[].attributes.body
Water is an unusual substance. When water freezes, it gets less dense. That is why ice cubes float in a glass of water. It also takes a lot of energy removal to freeze water, and the air is usually much colder than the earth at the bottom of the lake. So the cold comes from the air above the lake, and starts freezing the water from the surface. As the ice is formed, it floats and stays at the surface of the lake until a solid sheet of ice is formed. This ice prevents the cold air from reaching the water beneath it - the ice acts like a blanket for the water in the lake and helps keep it warmer than it otherwise would be. So a lot of things cause the lake to freeze only on top. Of course, if it stayed cold enough for long enough, the lake would freeze solid.

# data[].attributes.headline
WAN NORHANIS AYUNI BINTI SHA'RANI 187759

# data[].attributes.subject
WAN NORHANIS AYUNI BINTI SHA'RANI 187759

# data[].attributes.body
Water is in the liquid phase of H₂O molecules, while ice is the solid phase.

Next is density, which tells us how tightly matter particles are packed together. Tightly packed matter is more dense than loosely packed matter. Also, less dense matter floats on top of more dense matter. So when you place ice cubes in your soft drink(which is mostly water) and your ice cubes float, you know that ice is less dense than water. This is a very special property of water. Almost every other type of matter gets more dense when it changes phase from a solid to a liquid, but water gets less dense. Why? Because ice is a crystal, which means it has a regular pattern with spaces in between molecules. The spaces in the crystal are larger than the spaces between molecules in the liquid. More space = less dense, so ice is less dense than water.

Now in lakes, in beginning of winter, and the temperature has just gotten below freezing. Air changes temperature faster than water -- this is why a swimming pool seems much warmer in the evening. The air cools down at night, but the pool water remains almost as hot as it was during the day. So although the air is freezing cold, the water isn't freezing yet. The water at the very top of the lake is in direct contact with the cold air, so it freezes first. And because ice is less dense than water, the sheet of ice doesn't sink. If the temperature stays very cold, the sheet of ice gets thicker, but the ice also acts as a barrier, or insulator, between the cold air and the warmer water underneath. The sheet of ice helps the rest of the water from becoming ice.

The fact that water freezes on the surface of a lake but not below it allows plants and fish to live through the winter in northern lakes and ponds. Imagine a lake without fish! So it is a good thing that H₂0 has the very strange property that its solid phase is less dense than its liquid phase.

# data[].attributes.body
Why the water get when the waterfreezes, it gets less dense. That is why ice cubes float in a glass of water. It also takes a lot of energy removal to freeze water, and the air is usually much colder than the earth at the bottom of the lake .So the cold comes from comes from the air above the lake, and starts freezing the water from the surfaces. As the ice is formed, it floats and stays at the surface of the lake until solid sheet of ice is formed.

# data[].attributes.headline
Ahmad Mursyidi Bin Ahmad Mustaman 189790

# data[].attributes.subject
Ahmad Mursyidi Bin Ahmad Mustaman 189790

# data[].attributes.body
The botttom of the lake does not get freeze during winter because ice is less dense than liquid water, and when a solid crust of ice is on a lake, the water underneath is under pressure. The freezing point drops with increasing pressure for a substance the liquid of which is denser than the solid. Furthermore, the earth below retains the warmth better and keep the bottom of the lake unfreeze while the upper parts of the lake are froze because the air is the source of the cold sensation.

# data[].attributes.body
Well,  H₂O is a special substance where its solid form is less dense than its liquid form unlike other substances.

When the winter cold wind blow on the surface of water, the surface water freezed and a thin layer of ice is form. When this process keeps going, the layer of ice is getting thinker and finally cover up the whole surface of the lake.

When this happened, the thicker layer of ice functions as a barrier or an insulator between the outer cold wind and the inner less cold lake water. It effectively reduce the heat from the water beneath the ice layer from escaping to the atmosphere. Hence, the bottom of a lake usually does not get freeze during winter.

# data[].attributes.body
187016
Water is an unusual substance. When water freezes, it gets less dense. That is why ice cubes float in a glass of water. It also takes a lot of energy removal to freeze water, and the air is usually much colder than the earth at the bottom of the lake. So the cold comes from the air above the lake, and starts freezing the water from the surface. As the ice is formed, it floats and stays at the surface of the lake until a solid sheet of ice is formed. This ice prevents the cold air from reaching the water beneath it - the ice acts like a blanket for the water in the lake and helps keep it warmer than it otherwise would be. So a lot of things cause the lake to freeze only on top. Of course, if it stayed cold enough for long enough, the lake would freeze solid. Also here are two reasons why.
(1) The air is the source of the cold, and the earth below retains warmth better. Thus, the surface is frozen, while underneath it is heated (or kept from freezing) from below.
(2)Ice is less dense than liquid water, and when a solid crust of ice is on a lake, the water underneath is under pressure. The freezing point drops with increasing pressure for a substance the liquid of which is denser than the solid

# data[].attributes.body
Water is an unusual substance. When water freezes, it gets less dense. That is why ice cubes float in a glass of water. It also takes a lot of energy removal to freeze water, and the air is usually much colder than the earth at the bottom of the lake. So the cold comes from the air above the lake, and starts freezing the water from the surface. As the ice is formed, it floats and stays at the surface of the lake until a solid sheet of ice is formed. This ice prevents the cold air from reaching the water beneath it - the ice acts like a blanket for the water in the lake and helps keep it warmer than it otherwise would be. So a lot of things cause the lake to freeze only on top. Of course, if it stayed cold enough for long enough, the lake would freeze solid.
Ice is less dense than water because of the way it forms a hexagonal crystalline structure. Each water molecule consists of two hydrogen atoms bonded to the bottom of an oxygen atom. When ice forms, the hydrogen atoms of one water molecule form weak hydrogen bonds with the top of the oxygen atoms of two other water molecules. Lining up the water molecules in this pattern takes up more space than having them jumbled randomly together (as is the case in liquid water). And because the same mass of molecules takes up more space when frozen, ice is less dense than liquid water. For this same reason, water below 4° Celsius becomes increasingly less dense as it gets colder. Close to freezing temperatures, the molecules in the liquid water begin to line up into the space-filling hexagonal structure.

# data[].attributes.body
When water freezes, it gets less dense. That is why ice cubes float in a glass of water. It also takes a lot of energy removal to freeze water, and the air is usually much colder than the earth at the bottom of the lake. So the cold comes from the air above the lake, and starts freezing the water from the surface.
Warm water generally gets more dense as it gets colder, and therefore sinks. This fact may lead you to believe that ice should form on the bottom of a lake first. But a funny thing happens to water as it gets even colder. Colder than 4° Celsius (39° Fahrenheit), water begins expanding and becomes less dense as it gets colder. As a result, close to freezing, colder water floats to the top and the warmer water sinks to the bottom. The density of water as a function of temperature can be seen in the plot on the right. Eventually, the coldest water, which has floated to the top of the lake in wintry conditions, freezes to form a layer of ice. Right when the water freezes to ice, the ice becomes significantly less dense than the water and continues to float on the lake's surface.
Ice is less dense than water because of the way it forms a hexagonal crystalline structure. Each water molecule consists of two hydrogen atoms bonded to the bottom of an oxygen atom. When ice forms, the hydrogen atoms of one water molecule form weak hydrogen bonds with the top of the oxygen atoms of two other water molecules. Lining up the water molecules in this pattern takes up more space than having them jumbled randomly together (as is the case in liquid water). And because the same mass of molecules takes up more space when frozen, ice is less dense than liquid water. For this same reason, water below 4° Celsius becomes increasingly less dense as it gets colder. Close to freezing temperatures, the molecules in the liquid water begin to line up into the space-filling hexagonal structure.

# data[].attributes.body
187595

# data[].attributes.body
There are few reasons why the bottom of lake does not get freeze during winter.

First of all is the air is the source of the cold, and the earth below retains warmth better. Thus, the surface is frozen, while underneath it is heated (or kept from freezing) from below.

Next,Ice is less dense than liquid water, and when a solid crust of ice is on a lake, the water underneath is under pressure. The freezing point drops with increasing pressure for a substance the liquid of which is denser than the solid

Moreover that, water is an unusual substance. When water freezes, it gets less dense. That is why ice cubes float in a glass of water. It also takes a lot of energy removal to freeze water, and the air is usually much colder than the earth at the bottom of the lake. So the cold comes from the air above the lake, and starts freezing the water from the surface. As the ice is formed, it floats and stays at the surface of the lake until a solid sheet of ice is formed. This ice prevents the cold air from reaching the water beneath which the ice acts like a blanket for the water in the lake and helps keep it warmer than it otherwise would be. So a lot of things cause the lake to freeze only on top. Of course, if it stayed cold enough for long enough, the lake would freeze solid.

# data[].attributes.body
187970

The meaning of lake from Thesaurus.com are a body of fresh or salt water on considerable size, surrounded by land or any similar body or pool of other liquid; an expanse of water entirely surrounded by land and unconnected to the sea except by rivers or streams related to adjective lacustrine. Lakes can be formed by glacier, tectonic plate movements, river from billabong and wind currents, and volcanic or meteorite activity. Some are only seasonal with drying up during parts of year.

The reason why only the upper part of layers of lakes is freezing are due to the density. When water freezes, it gets less dense. That is why ice cubes float in a glass of water. It also takes a lot of energy removal to freeze water, and the air is usually much colder than the earth at the bottom of the lake. So the cold comes from the air above the lake, and starts freezing the water from the surface

Lakes or fresh water are salty because there is in a region the water are evaporates more quickly due to high concentration. The study of lakes and other freshwater basins is known as limnology. Lakes are divided into two which are natural and artificial which is man-made.  The natural lakes in Malaysia are Tasik Bera and Tasik Chini while artificial is Tasik Kenyir.

# data[].attributes.body
There are three reasons why the bottom lake does not get freeze during the winter.

1) The air is the source of the cold, and the earth below retains warmth better. Thus, the surface is frozen, while underneath it is heated (or kept from freezing) from below.

2) Ice is less dense than liquid water, and when a solid crust of ice is on a lake, the water underneath is under pressure. The freezing point drops with increasing pressure for a substance the liquid of which is denser than the solid

3) Water is an unusual substance. When water freezes, it gets less dense. That is why ice cubes float in a glass of water. It also takes a lot of energy removal to freeze water, and the air is usually much colder than the earth at the bottom of the lake. So the cold comes from the air above the lake, and starts freezing the water from the surface. As the ice is formed, it floats and stays at the surface of the lake until a solid sheet of ice is formed. This ice prevents the cold air from reaching the water beneath it - the ice acts like a blanket for the water in the lake and helps keep it warmer than it otherwise would be. So a lot of things cause the lake to freeze only on top. Of course, if it stayed cold enough for long enough, the lake would freeze solid

# data[].attributes.body
The first thing to think is about the phase of matter which is gas, liquid and solid. Water is the name of the liquid phase of H₂O molecules which it particles are close together and moving slowly around each other , and ice is the name of the solid phase where it particles are locked in position and hard to move.
The second thing is about density.. When water freezes, it gets less dense. That is why ice cubes float in a glass of water. It also takes a lot of energy removal to freeze water, and the air is usually much colder than the earth at the bottom of the lake. So the cold comes from the air above the lake, and starts freezing the water from the surface. As the ice is formed, it floats and stays at the surface of the lake until a solid sheet of ice is formed. This ice prevents the cold air from reaching the water beneath it - the ice acts like a blanket for the water in the lake and helps keep it warmer than it otherwise would be. So a lot of things cause the lake to freeze only on top. Of course, if it stayed cold enough for long enough, the lake would freeze solid.

# data[].attributes.body
Water is an unusual substance. When water freezes, it gets less dense. That is why ice cubes float in a glass of water. It also takes a lot of energy removal to freeze water, and the air is usually much colder than the earth at the bottom of the lake. So the cold comes from the air above the lake, and starts freezing the water from the surface. As the ice is formed, it floats and stays at the surface of the lake until a solid sheet of ice is formed. This ice prevents the cold air from reaching the water beneath it - the ice acts like a blanket for the water in the lake and helps keep it warmer than it otherwise would be. So a lot of things cause the lake to freeze only on top. Of course, if it stayed cold enough for long enough, the lake would freeze solid.

Ice is less dense than liquid water, and when a solid crust of ice is on a lake, the water underneath is under pressure. The freezing point drops with increasing pressure for a substance the liquid of which is denser than the solid.

# data[].attributes.body
Why water get freeze at upper are actually effected by the form of the particle. Water is known as liquid phase while ice is known in solid fom. Density aslo the aspect why ice are floating in ice, in science the more the tightly of the particles, the more the dense of the particles. So as we can see ice have regular shape which it have more space rather than the water so that it less dense than water. That why ice are floating at upper of the water.

Besides, the temperature also influence the density of the ice forming. When there is the changing of the temperature the water forming also can be effected. At the low temperature the water will change their  transitional stage from liquid to solid so that the density of the water also change. So the density will reduce in ice stage. So it will float at the upper of the water. If the temperature at the lower point, the sheet of ice will becomes thicker, the ice also acts as a barrier, or insulator, between the cold air and the warmer water underneath. The sheet of ice can helps the rest of the water from becoming ice.

# data[].attributes.headline
MUHAMMAD ALIFF HAIKAL BIN ZAINUDIN 187854

# data[].attributes.subject
MUHAMMAD ALIFF HAIKAL BIN ZAINUDIN 187854

# data[].attributes.body
This can happen not just for water, but for many substances that form crystals in their solid state. The molecules of a liquid behave a little differently than those in either the solid state (where they are tightly locked and are in a orderly arrangement or crystal lattice) or gas state (where they are completely independent).The conversion of gas into solid directly is known as sublimation in which the temperature decreases sharply. In still water, the whole volume cools down to 4°C as the colder water sinks to the bottom, a thin layer at the top surface can then quickly cool to 0°C while floating on the denser water below, and start to freeze. In moving water the whole volume has to cool to 0°C before freezing starts. Because of the high specific heat of water and the latent heat of freezing, it would take a very long time (probably several days) even for still water to "freeze solid" with an air temperature of only -1 °C.

Simply cooling the molecules in a liquid does not make them solid. The molecules must begin to arrange themselves in orderly crystal lattice, and this takes a little more energy (called the latent heat of fusion). Forming a solid from individual liquid molecules is similar, the first few molecules must move into proper position and alignment to start building crystal lattice. Once this lattice begins to form, it becomes much easier for other liquid molecules to attach and continue growing the crystal lattice. The colder a liquid becomes, the more likely it is that some of the molecules will form that first crystal, but if they are not moving around much it may not happen.

# data[].attributes.body
This is due to the fact that the water-air boundary has a higher heat exchange rate. Thus a thin ice layer forms there first. Ice floats. More importantly, it inhibits convection of heat from the body of water to the atmosphere. As the water underneath the layer of ice cools, it sinks, mixing with warmer subsurface waters. This inhibits the freezing process by roughly the square of the surface ice thickness.
Thus, the top of the lake freezes solid and forms a layer of ice, while the bottom of the lake continues to remain in liquid form and possesses higher temperature compared to the top most layer.

# data[].attributes.body
Water is the name of the liquid phase of H₂O molecules, and ice is the name of the solid phase. Water is an unusual substance. When water freezes, it gets less dense. That is why ice cubes float in a glass of water. It also takes a lot of energy removal to freeze water, and the air is usually much colder than the earth at the bottom of the lake. So the cold comes from the air above the lake, and starts freezing the water from the surface. As the ice is formed, it floats and stays at the surface of the lake until a solid sheet of ice is formed. This ice prevents the cold air from reaching the water beneath it - the ice acts like a blanket for the water in the lake and helps keep it warmer than it otherwise would be. So a lot of things cause the lake to freeze only on top. Of course, if it stayed cold enough for long enough, the lake would freeze solid.

# data[].attributes.body
When water freeze, it gets less dense. That is why ice cubes float in a glass of water. It also takes a lot of energy removal to freeze water, and the air is usually much colder than the earth at the bottom of the lake. So the cold comes from the air above the lake, and starts freezing the water from the surface.

# data[].attributes.body
There are two reasons why.
(1) The air is the source of the cold, and the earth below retains warmth better. Thus, the surface is frozen, while underneath it is heated (or kept from freezing) from below.
(2)Ice is less dense than liquid water, and when a solid crust of ice is on a lake, the water underneath is under pressure. The freezing point drops with increasing pressure for a substance the liquid of which is denser than the solid

# data[].attributes.body
Because the water density at 4 ℃ maximum, thermal expansion and contraction effect in the water 4 ℃ failure. When the outside temperature decreases, the lake will also cool down, but the water at 4 ° C will sink to the bottom because it has the highest density, and the density of ice is much smaller than that of water, which of course floats on it. This icing always starts at the surface of the lake. At the bottom of the lake is 4 ° C. Before the water is completely frozen, it should be at the bottom of the lake and the temperature should be 13 ° C as long as there is still liquid water. Of course there will be heat transfer, but "frozen three feet, non-day cold." This sentence also shows that the heat transfer is slow, even if the external temperature is low enough, let the entire lake to freeze, it will take a long time.

# data[].attributes.body
Water density changes with the water temperature. Part of the thermal energy of the water molecules on the lake surface will flow to the cooler air. When the temperature of surrounding starts decreasing, the temperature of water will also decrease in the following manner:

Firstly, the surface water is going to cool; As the water cools the density increases and the surface water drowns to the bottom and the bottom water rises up. This will continue till the whole water comes at 4 degree Celsius.

Now, further cooling will occur but as the surface water is going to get affected first, it will cool first. But now the density won’t increase, instead the density is going to decrease, which means that the surface water, instead of drowning (like before), would keep on floating on the top, disallowing the bottom water to come up and further cool. The warmer water under the surface will rise gradually because of its smaller density, convection thus takes place and the whole lake will be cooled down. So, the surface water keeps on cooling till it gets converted to ice continuing to float on the surface of water keeping the inside of water at a temperature of 4 degree Celsius. This is because the density is in decreasing order of- Solid> Liquid> Gas. Hence, the density of water in solid form (ice) is smaller than the density of water in liquid form. Therefore, we can say that water with a lower temperature on the lake surface will freeze first and then the freezing will spread to the lake bottom. Because heat is transmitted by conduction, the cooling rate is very slow. The water temperature under the ice layer usually maintains.

This anomaly allows the aquatic organism to survive in freezing cold, as the temperature below is warmer than above. If water does not have this special property, we can imagine that water will start to freeze from the bottom and convection will increase the rate of freezing.

# data[].attributes.body
189350

# data[].attributes.body
The first thing need to think about is the phases of matter: Gas, liquid, and solid. Matter is made up of particles called atoms and molecules. If the particles are moving around very fast and they are spread far apart the matter is in the gas phase. If the particles are closer together and moving slowly around each other the matter is in a liquid phase. Finally, if the particles are locked in position and not hardly moving at all the matter is in a solid phase.

Water is the name of the liquid phase of H₂O molecules, and ice is the name of the solid phase.

The second thing we need to think about is density, which tells us how tightly matter particles are packed together. Tightly packed matter is more dense than loosely packed matter. Also, less dense matter floats on top of more dense matter. So when you place ice cubes in your soft drink(which is mostly water) and your ice cubes float, you know that ice is less dense than water. This is a very special property of water. Almost every other type of matter gets more dense when it changes phase from a solid to a liquid, but water gets less dense. Why? Because ice is a crystal, which means it has a regular pattern with spaces in between molecules. The spaces in the crystal are larger than the spaces between molecules in the liquid. More space = less dense, so ice is less dense than water.

So now we understand why ice floats on top of water, but how does this work on a lake? Imagine that it is the beginning of winter, and the temperature has just gotten below freezing. Air changes temperature faster than water -- this is why a swimming pool seems much warmer in the evening. The air cools down at night, but the pool water remains almost as hot as it was during the day. So although the air is freezing cold, the water isn't freezing yet. The water at the very top of the lake is in direct contact with the cold air, so it freezes first. And because ice is less dense than water, the sheet of ice doesn't sink. If the temperature stays very cold, the sheet of ice gets thicker, but the ice also acts as a barrier, or insulator, between the cold air and the warmer water underneath. The sheet of ice helps the rest of the water from becoming ice!

The amazing fact that water freezes on the surface of a lake but not below it allows plants and fish to live through the winter in northern lakes and ponds. Imagine a lake without fish! So it is a good thing that H₂0 has the very strange property that its solid phase is less dense than its liquid phase.

# data[].attributes.body
In what i read, while water is moving, its temperatue can drop below zero and it doesn't freeze. Obviously, faster moving rivers are less likely to freeze.
For lakes, water's unique density behaviour protects them from freezing. Unlike almost all substances, the solid form of water (ice) is less dense than the liquid form. Ice cubes float.
So when lakes freeze, the ice stays at the top. This insulates the remaining water from the colder air above. If ice cubes sank, then lakes could freeze all the way to the bottom: the ice that formed would fall to the bottom, continually exposing the top water to the cold air.

# data[].attributes.body
The water unique density behavior protects them from freezing. Unlike almost all substances, the solid form of water (ice) is less dense than the liquid form. Ice cubes float.

So when lakes freeze, the ice is formed and stays at the surface of the top until a solid sheet of iced is formed. This insulates the remaining water from the colder air above.This ice prevents the cold air from reaching the water beneath it - the ice acts like a blanket for the water in the lake and helps keep it warmer than it otherwise would be. So a lot of things cause the lake to freeze only on top.
Of course, if it stayed cold enough for long enough, the lake would freeze solid. If ice cubes sank, then lakes could freeze all the way to the bottom the ice that formed would fall to the bottom, continually exposing the top water to the cold air.

Example : Putrajaya Lake, Malaysia

# data[].attributes.body
The water at the very top of the lake is in direct contact with the cold air, so it freezes first. And because ice is less dense than water, the sheet of ice doesn't sink. If the temperature stays very cold, the sheet of ice gets thicker. B
ut the ice also acts as a barrier, or insulator, between the cold air and the warmer water underneath. This ice prevents the cold air from reaching the water beneath it.

# data[].attributes.body
siti nor hidayah 189512

# data[].attributes.body
When water freezes, it gets less dense. That is why ice cubes float in a glass of water. It also takes a lot of energy removal to freeze water, and the air is usually much colder than the earth at the bottom of the lake. So the cold comes from the air above the lake, and starts freezing the water from the surface.
The bottom of lake does not get freeze during the winter because  water is a good store of heat. The surface is the first to freeze due to air currents, and that ice provides additional insulation to hold the heat below in.
Heat is also coming from the inside of the Earth. The Earth's core is very hot, and its heat moves towards the surface. This movement of heat to the surface is called the geothermal heat flux. The geothermal heat flux can stop the ground from freezing. Even in very cold areas, the ground can only freeze so far before the geothermal heat flux stops it.
Heat from volcanoes, rivers, lakes, and other sources can also spread through the ground. This heat keeps some areas unfrozen, even though surface temperatures are low.

# data[].attributes.body
The reason is  the air is the source of the cold, and the earth below retains warmth better. Thus, the surface is frozen, while underneath it is heated  from below.  Ice is less dense than liquid water, and when a solid crust of ice is on a lake, the water underneath is under pressure. The freezing point drops with increasing pressure for a substance the liquid of which is denser than the solid.
The longer the cold period, the deeper the ground will freeze. But the depth of frozen ground is limited, because Earth is warm deep inside. The ground stores a lot of the Sun's heat and reflects the rest into the air. Snow and ice are light colored and reflect more heat away.  The top layer of ground may respond to conditions on the surface, but the layers below may not change as quickly.

Heat is also coming from the inside of the Earth. The Earth's core is very hot, and its heat moves towards the surface. This movement of heat to the surface is called the geothermal heat flux. The geothermal heat flux can stop the ground from freezing. Even in very cold areas, the ground can only freeze so far before the geothermal heat flux stops it.
Heat from volcanoes, rivers, lakes, and other sources can also spread through the ground. This heat keeps some areas unfrozen, even though surface temperatures are low.

# data[].attributes.body
Warm water generally gets more dense as it gets colder, and therefore sinks. This fact may lead you to believe that ice should form on the bottom of a lake first. But a funny thing happens to water as it gets even colder. Colder than 4° Celsius (39° Fahrenheit), water begins expanding and becomes less dense as it gets colder. As a result, close to freezing, colder water floats to the top and the warmer water sinks to the bottom. The density of water as a function of temperature can be seen in the plot on the right. Eventually, the coldest water, which has floated to the top of the lake in wintry conditions, freezes to form a layer of ice. Right when the water freezes to ice, the ice becomes significantly less dense than the water and continues to float on the lake's surface.

Ice is less dense than water because of the way it forms a hexagonal crystalline structure. Each water molecule consists of two hydrogen atoms bonded to the bottom of an oxygen atom. When ice forms, the hydrogen atoms of one water molecule form weak hydrogen bonds with the top of the oxygen atoms of two other water molecules. Lining up the water molecules in this pattern takes up more space than having them jumbled randomly together (as is the case in liquid water). And because the same mass of molecules takes up more space when frozen, ice is less dense than liquid water. For this same reason, water below 4° Celsius becomes increasingly less dense as it gets colder. Close to freezing temperatures, the molecules in the liquid water begin to line up into the space-filling hexagonal structure.

# data[].attributes.body
The bottom of lake does not get freeze during the winter because  water is a good store of heat. The surface is the first to freeze due to air currents, and that ice provides additional insulation to hold the heat below in.

Furthermore, solids and liquids have molecules very closely packed together, where gas has molecules very spread apart. If the air is the coldest, those molecules will grab heat energy from the ground and water, but it takes a while to make a huge difference. For example, cooling off a hot frying pan is much quicker when dipping it into room temperature water rather than letting it set in room temperature air.

for example,  animals like seals, penguins, walruses and a wide variety of sea birds are all fish eaters. They live in the Arctic and Antarctic Circle, amidst the icecaps. The land is completely frozen. Yet these animals manage to live in this region.  Jellyfish, fragile creature of the sea at arctic sea

# data[].attributes.body
Lakes freeze from the top down. Ice is less dense than water, which is why ice floats. The density of liquid water is determined by its temperature, and water is most dense at about 40 F.

Once the surface water falls to 32 F, it freezes. The freezing then spreads downward into the lake and the ice thickens .

At some point, the ice layer itself on a lake will act as an insulator, preventing the cold air above the ice from removing heat from the unfrozen water below. This is why lakes don’t typically freeze completely from top to bottom. The ultimate thickness of the ice layer depends on many variables, including the size and shape of the lake, the air temperature, and the duration of the cold air above the ice. In some cases, very shallow lakes or lakes on mountain tops may freeze completely

# data[].attributes.body
Water is an unusual substance. When water freezes, it gets less dense. That is why ice cubes float in a glass of water. It also takes a lot of energy removal to freeze water, and the air is usually much colder than the earth at the bottom of the lake. So the cold comes from the air above the lake, and starts freezing the water from the surface. As the ice is formed, it floats and stays at the surface of the lake until a solid sheet of ice is formed. This ice prevents the cold air from reaching the water beneath it - the ice acts like a blanket for the water in the lake and helps keep it warmer than it otherwise would be. So a lot of things cause the lake to freeze only on top. Of course, if it stayed cold enough for long enough, the lake would freeze solid.

# data[].attributes.body
When water freezes, it gets less dense. That is why ice cubes float in a glass of water. It also takes a lot of energy removal to freeze water, and the air is usually much colder than the earth at the bottom of the lake. So the cold comes from the air above the lake, and starts freezing the water from the surface.

Once the surface water falls to 32 F, it freezes. The freezing then spreads downward into the lake and the ice thickens .

This ice prevents the cold air from reaching the water beneath it - the ice acts like a blanket for the water in the lake and helps keep it warmer than it otherwise would be. So a lot of things cause the lake to freeze only on top. Of course, if it stayed cold enough for long enough, the lake would freeze solid.

Example :

In the winter, temperatures in a lake get close enough to freezing that the colder water is less dense and floats to the top.

Below 4° Celsius, water becomes less dense as it gets colder, causing water about to freeze to float to the top.

# data[].attributes.body
There are two reasons why.
(1) The air is the source of the cold, and the earth below retains warmth better. Thus, the surface is frozen, while underneath it is heated (or kept from freezing) from below.

(2) Ice is less dense than liquid water, and when a solid crust of ice is on a lake, the water underneath is under pressure. The freezing point drops with increasing pressure for a substance the liquid of which is denser than the solid.

# data[].attributes.body
Colder than 4° Celsius (39° Fahrenheit), water begins expanding and becomes less dense as it gets colder. As a result, close to freezing, colder water floats to the top and the warmer water sinks to the bottom. Eventually, the coldest water, which has floated to the top of the lake in wintry conditions, freezes to form a layer of ice. Right when the water freezes to ice, the ice becomes significantly less dense than the water and continues to float on the lake's surface.
As a lake cools from above 4° C, the surface water loses heat, becomes more dense and sinks. This process continues until all the water in the lake is at 4° C, when the density of water is at its maximum. With further cooling (and without mechanical mixing) a stable, lighter layer of water forms at the surface. As this layer cools to its freezing point, ice begins to form on the surface of the lake.

In the winter, temperatures in a lake get close enough to freezing that the colder water is less dense and floats to the top.

# data[].attributes.body
Water is an unusual substance. When water freezes, it gets less dense. That is why ice cubes float in a glass of water. It also takes a lot of energy removal to freeze water, and the air is usually much colder than the earth at the bottom of the lake. So the cold comes from the air above the lake, and starts freezing the water from the surface. As the ice is formed, it floats and stays at the surface of the lake until a solid sheet of ice is formed. This ice prevents the cold air from reaching the water beneath it - the ice acts like a blanket for the water in the lake and helps keep it warmer than it otherwise would be. The pressure on the water at a specific depth also factors in. Just think of water expanding as it freezes. If there is a pressure on a layer of water (like at the bottom, being pressed down by the water and ice above it) it requires a lower temperature than 32 degree F to freeze. So a lot of things cause the lake does not freeze during the winter. Of course, if it stayed cold enough for long enough, the lake would freeze solid.

Melting ice draws heat from the environment