The document discusses the atmosphere and weather. It defines the atmosphere as a thin blanket of air surrounding the Earth, made up of gases like oxygen and carbon dioxide. Weather is defined as the current condition of the atmosphere at a given time and place, and can vary depending on time of day, seasons, and location. Key factors that are measured to describe weather include air temperature, wind speed and direction, humidity, precipitation, and air pressure.

2. A boy sleeping & covered with
a blanket
Do you that
Earth has a
blanket too?
Really, How is
that?
Yes, It is called
atmosphere

3. What is Atmosphere?
- It is a thin blanket of air that surrounds our planet
Earth.
- - It is made up of many gases.
“Oxygen – Carbon dioxide – ..etc”
It’s a mixture of gases

4. Weather
The weather is so
cold & snowy

5. What is the weather?
It’s the condition of
atmosphere at a given
time & place
Christmas time
USA

6. - Weather changes depending on many conditions:
Does weather changes?
1- Time of the day
Example: In the Desert
During the day During the night
- The weather is very hot - The weather is cold

7. 2- Seasons
Spring
It’s rainy & warm
Summer
It’s hot & sunny
Winter
It’s cold & snowy
Autumn
It’s windy

8. 3- Place

9. - Measuring the weather depends on many factors:
How to measure weather?
1- Air Temperature
2- Wind speed & direction
3- Humidity
4- Precipitation
5- Air pressure

10. 1- Air temperature
-It describes how hot or cold the air is.
Example: During Summer During Winter
- Temperature is high - Temperature is low
-Air Temperature is measured using: Thermometer
“ In Celsius / Fahrenheit”

11. 2- Wind
There is a strong wind, the weather is windy

12. What’s the wind?
It’s the moving air
“When the sun heats the surface of the Earth, the
surface warms up the air, so the air moves up & the
cold air gets down causing the wind”
- We measure the wind speed
using: Anemometer
- We measure the wind direction
using: Wind vane
It points to the direction
from which the wind blows
The faster the wind
blows, the faster
the cups spin

13. 3- Humidity
- Some times the air around us feels damp & sticky
like: In Alexandria
- This is because of the “Humidity”
{Humidity: is the measure of how much moisture
(water vapor)is in the air}

14. -The more the water vapor in the air, the more the
humidity is in the air.
-Examples:
Desert Rain forest
- Has low humidity - Has high humidity
- We measure the humidity in the air using: Hygrometer

15. 4- Precipitation
Any form of water that fall from the clouds is precipitation
Does this
mean that
rain is
precipitation?
Yes, of course..
And snow too
is a kind of
precipitation
I wonder how
many kinds of
precipitation
are there?

16. Kinds of precipitation
Rain Snow Sleet Hail
“Flakes of snow
mixed with water
drops”
“Chunks of snow”
As the size of small
ball
Snow fall as
crystals”

17. -We measure the amount of rain fall using:
Rain gauge

18. 5- Air pressure
- They are measuring their
weight “how heavy they are”
Really? How
is that?
Yes, it’s the
air pressure
Do you know
that air has
weight too?

19. What’s air pressure?
- It’s the weight of the air on a certain area.
OR
-It’s the force of air pushing on a certain area.

20. - Air pressure is around us, but we don’t feel it.
- While, when we go diving or when we are in an
airplane, we fell that our ear is plugged, this is because
of the air pressure change.
Examples

21. - Particles of the cool air are closer together than the
particles of warm air.
- Particles of warm air are not packed together “have less
density”.
- So, particles of cool air will weight more than particles
of warm air.
So, Cool air has more pressure than warm air
-This why, As we heat air, it’s pressure decrease.
Which has more air pressure?
“Cool air / Warm air”

22. Where to find high / low pressure ?
- As air becomes hot, its particles moves away from each other
& air becomes light, so it moves up & its pressure decrease.
-While; cold air particles are close together, so air becomes
heavy ,it goes down & its pressure increase.
-This is why:
As we go up, pressure decrease
“because this is where hot air is found”

23. (Places with low pressure)
Mountains – Top of buildings
Examples

24. (Places with high pressure)
Valleys– Submarines

25. - We use a barometer to measure air pressure.

26. Remember:
Don’t get confused between the barometer & the
hygrometer..