Activa JavaScript para disfrutar de los vídeos de la Mediateca.
1º ESO/ELEMENTS OF WEATHER - Contenido educativo
Ajuste de pantallaEl ajuste de pantalla se aprecia al ver el vídeo en pantalla completa. Elige la presentación que más te guste:
Elements of weather. We know that temperature, atmospheric pressure, winds, humidity, clouds, and precipitation are the elements of weather.
00:00:00
Let us know more about them.
00:00:18
Temperature.
00:00:23
The degree of heat of an object or the degree of heat at a place is known as temperature.
00:00:23
Thus, the quantity by which you can compare the hotness or coldness of bodies is called temperature.
00:00:34
Temperature is measured in degree Celsius.
00:00:44
Celsius is also called centigrade.
00:00:49
Temperature is measured by an instrument called the thermometer.
00:00:52
Temperature on a Celsius scale is read in degree Celsius.
00:01:00
Following are the factors on which atmospheric temperature of a place depends.
00:01:06
a. Nearness of the place to the Earth's surface.
00:01:12
b. Latitude of the place.
00:01:17
c. Altitude of the place.
00:01:21
d. Height of the place above sea level
00:01:23
e. Distance of the place from the sea
00:01:28
The earth's surface gets heated due to the heat of the sun.
00:01:32
Hence, the air near its surface gets heated first.
00:01:39
Then, layer by layer, the air becomes warm.
00:01:44
Hence, the temperature near the earth's surface is higher.
00:01:49
and decreases as we go further away from the earth.
00:01:53
Atmospheric Pressure
00:02:01
You might have enjoyed boating with your parents several times.
00:02:02
Have you observed that when you sit on a boat,
00:02:09
its one side is pressed down sideways?
00:02:12
Actually, it happens due to the weight of your body,
00:02:17
which you exert on the side of the boat.
00:02:21
You must have read in your science textbook that any object has weight.
00:02:24
Air also has weight.
00:02:32
It is a highly compressible mixture of gases which applies pressure on the Earth's surface by exerting its weight.
00:02:35
Thus, atmospheric pressure is defined as
00:02:44
the pressure exerted by the vertical column of air lying above a particular area.
00:02:49
Atmospheric pressure is measured by using a barometer.
00:02:57
The unit of measurement of atmospheric pressure is millibar, written as mb.
00:03:01
The variation in the atmospheric pressure from one place to another
00:03:11
affects all weather changes.
00:03:16
For example, the rising pressure makes the weather fine
00:03:20
while decreasing air pressure makes the weather cloudy and rainy.
00:03:24
All these variations or changes in atmospheric pressure depend upon some factors.
00:03:31
Let us know about these factors.
00:03:38
Following are the factors on which atmospheric pressure of a place depends.
00:03:43
1. Temperature
00:03:49
2. Altitude
00:03:51
3. Density of the air
00:03:53
Let us discuss these factors one by one.
00:03:57
1. Temperature
00:04:04
There is an inverse relationship between air pressure and temperature.
00:04:05
When the temperature of a place rises, the volume of the surrounding air starts to increase.
00:04:13
This makes the air less dense.
00:04:21
Due to the lower density, the air exerts a lesser pressure on the surface.
00:04:26
When the temperature falls, the air becomes denser.
00:04:32
That is, the weight of air increases.
00:04:38
Due to the higher density, the column of air exerts a greater pressure on the surface.
00:04:43
So, we can say that the hotter the place, the lesser the atmospheric pressure
00:04:50
and the colder the place, the higher the atmospheric pressure.
00:04:57
2. Altitude
00:05:05
Air is compressible and it concentrates near the Earth's surface.
00:05:06
The upper layers of the atmosphere exerts more pressure on the lower layers on the surface of the Earth,
00:05:14
thus increasing the density of air.
00:05:24
Therefore, the atmospheric pressure near the Earth's surface is greater.
00:05:27
As we move upwards from the Earth's surface, the air becomes lighter,
00:05:34
which results in a low atmospheric pressure condition.
00:05:41
This clearly indicates that the rate of atmospheric pressure varies inversely with height.
00:05:46
3. Density of air
00:05:54
The dense air is heavier than the thin air.
00:05:57
Therefore, it exerts more pressure on the Earth's surface,
00:06:02
while thin air exerts less pressure on the surface.
00:06:08
The dense air is generally found near the surface of the Earth,
00:06:14
especially at the ocean's surface.
00:06:20
That is why we find more atmospheric pressure at the sea level
00:06:22
than at the top of hills or mountains.
00:06:29
Wind
00:06:35
Air always remains in motion.
00:06:36
Sometimes it moves horizontally and sometimes vertically.
00:06:40
The horizontal movement of air is called wind.
00:06:47
Air moves horizontally from an area of high pressure to an area of low pressure.
00:06:51
Thus, the air moving in a direction which is essentially parallel, horizontal, with the Earth's surface is called wind.
00:07:00
The speed of wind is measured in kilometers per hour.
00:07:11
The instrument used to measure the speed of wind is called an anemometer.
00:07:17
Humidity
00:07:27
We know that water vapor is always present in the atmosphere.
00:07:28
The amount of this water vapor is called humidity.
00:07:34
The moistness or the dryness of the air depends upon the atmospheric humidity.
00:07:39
Weather is said to be humid when the water vapour content in air is higher and it is dry weather when the water vapour content in the air is lower.
00:07:48
Rainfall depends on the level of atmospheric humidity.
00:08:05
Rainfall is high in areas like Mumbai because it is near the Arabian Sea.
00:08:09
It is low in areas which are far away from water bodies.
00:08:18
The instrument used to measure humidity of a place is a dry and wet bulb thermometer.
00:08:26
Humidity is given in percentage.
00:08:34
clouds water from the water bodies like lakes rivers seas and oceans evaporates due to the
00:08:37
sun's rays and form vapor this vapor mixes with the atmosphere it rises higher and higher along
00:08:48
with the air.
00:08:59
Due to the low temperature
00:09:02
at higher altitudes,
00:09:03
the water vapor
00:09:06
gets converted into water
00:09:07
droplets around
00:09:09
dust particles.
00:09:11
This process is known
00:09:14
as condensation.
00:09:16
These water
00:09:18
particles float in the
00:09:19
atmosphere. A collection
00:09:21
of such minute water
00:09:24
particles is known as
00:09:26
a cloud.
00:09:28
Precipitation. The wind blows the clouds from one place to another. We get rainfall from the clouds. This is called precipitation.
00:09:31
- Subido por:
- Alicia M.
- Licencia:
- Dominio público
- Visualizaciones:
- 275
- Fecha:
- 10 de abril de 2021 - 19:59
- Visibilidad:
- Público
- Centro:
- IES LA SENDA
- Duración:
- 09′ 47″
- Relación de aspecto:
- 1.78:1
- Resolución:
- 1920x1080 píxeles
- Tamaño:
- 253.60 MBytes