The document discusses various topics related to weather including: 1. It defines weather as the short-term state of the atmosphere varying from minutes to weeks and is influenced by factors like temperature, precipitation and wind. 2. It explains key weather phenomena like the water cycle, air masses, jet streams, weather fronts, and how different types of precipitation like rain, snow and hail are formed. 3. It discusses tropical weather patterns including the intertropical convergence zone and how typhoons are formed, and also explains storm surge and the factors that influence its height.

1. THE WEATHERBy: Mhykaela T. Bautista
BSED II-T Socstud

2. Weather is the day-to-day state of the atmosphere, and its short-
term variation in minutes to weeks. People generally think of
weather as the combination of temperature, humidity,
precipitation, cloudiness, visibility, and wind.
What is Weather?

3. What influences the weather
and climate pattern?

4. The Water Cycle
As the sun warms the surface of the Earth, water rises in the form of
water vapour from lakes, rivers, oceans, plants, the ground, and other
sources. This process is called evaporation. Water vapour provides the
moisture that forms clouds; it eventually returns to Earth in the form
of precipitation, and the cycle continues.

6. Air Masses
When air hovers for a while over a surface area with uniform humidity and temperature,
it takes on the characteristics of the area below. For example, an air mass over the tropical
Atlantic Ocean would become warm and humid; an air mass over the winter snow and ice
of northern Canada would become cold and dry. These massive volumes of air often
cover thousands of miles and reach to the stratosphere. Overtime, mid-latitude cyclonic
storms and global wind patterns move them to locations far from their source regions.
What happens when 2 air masses meet? The cold air pushes the hot air upwards, when
going up the temperature drops and the air can't hold as much water when it is warm, so
the cold water molecules condense and form clouds.

7. Jet Stream
A jet stream is the name given to the area of air above where two air masses of different
temperature converge e.g. a cold front meeting a warm front. The greater the temperature
difference between the air masses, the greater the air pressure difference, and the faster the wind
blows in the jet stream. This river of air has wind speeds which often exceed 100 mph, and
sometimes over 200 mph. Jet streams more commonly form in the winter, when there is a greater
difference between the temperature of the cold continental air masses and warm oceanic air
masses. This meandering current of high-speed wind, a jet stream is usually found around five to
ten miles above Earth’s surface. It generally flows west to east, often in a non-continuous wavy
fashion, with cold, Equatorward dips and warm, Poleward bulges.

9. Weather Fronts
The transition zone between two air masses of different humidity and
temperature is called a front. Along a cold front, cold air displaces warm
air; along a warm front, warm air displaces cold air. When neither air mass
displaces the other, a stationary front develops. Towering clouds and
intense storms may form along cold fronts, while widespread clouds and
rain, snow, sleet, or drizzle may accompany warm fronts.

11. What are the building
blocks of weather?

12. 1. Wind
Wind is moving air and is caused by differences in air
pressure within our atmosphere. Air under high pressure
moves toward areas of low pressure. The greater the
difference in pressure, the faster the air flows.

13. 2. Temperature
Temperature is the measure of how cold or hot somewhere is.
Temperature is usually higher during the day than at night. Rural
areas (the countryside) are often cooler than towns and cities.
This is because there are more buildings and factories ( known as
'heat islands') which absorb heat during the day, releasing it
slowly at night and warming the surrounding air.

14. 3. Sunshine
The amount of sunshine we have depends on latitude and how much cloud
there is in the sky. In some of the world's deserts the number of sunshine
hours is very high, more than 3,600 hours each year. In the Eastern Sahara
desert, the sun is covered by clouds for less than 100 hours a year. In Britain
we have from 1,850 hours in Southern England to 1,200 hours in North
Scotland. There is usually more sunshine where atmospheric pressure is
higher.

15. 4. Visibility
Visibility is simply how far you can see. In weather terms it is how
clear the atmosphereand air are, taking into account fog, mist and urban
pollution. Fog and mist are like clouds on the ground. They are made up
of lots of tiny water droplets, which is why you can sometimes get wet
when walking through fog. When there is a light breeze, clear skies and
damp air, moisture in the air condenses near the ground making fog or
mist.

16. 5. Pressure
Pressure is the weight of the atmosphere on the earth’s surface. This
atmospheric pressure is lower at the top of mountains and highest at sea
level. This is beacuse all the air above the sea pushes down on its' surface.
Rapid drops in air pressure mean unstable conditions and a storm is on its
way, while rises in pressure mean conditions are more stable and fair
weather is returning.

17. 6. Humidity
Humidity is how much water vapour is in the atmosphere.
Like a sponge, the air is always evaporating and storing
water from rivers, lakes and oceans. In tropical parts of the
world, warm air is able to hold more water vapour and
humidity is higher as a result.

18. 7. Clouds
Clouds are made up of millions of tiny water droplets. Clouds are made
when quite warm, moist air rises into the sky where it cools down
and condenses. Clouds can form in a few minutes or over a number of
hours. There are many different types of cloud and looking at them can
help you to predict the weather.

19. • How clouds are formed?

21. • What is precipitation?

22. 8. Precipitation
Precipitation is the release of water from the atmosphere to the
earth’s surface as a solid or liquid. It includes rain, snow, hail, sleet
and dew.

23. • What are the different types
of precipitation?

24. Rain
Drops of liquid water fall from the clouds when water vapour condenses around
dust particles in the clouds, forming tiny droplets that eventually get too big for
the cloud to hold so they fall, growing larger as they collect more water on their
way down.

25. Snow
Snow is ice that falls from the sky. Each snowflake is a delicately complex arrangement of ice crystals. A
snowflake forms when water vapor sublimates, or turns directly from a gas into its solid form, ice.

26. Hail
Hail is ice that falls from the sky, often in round shapes. Hailstones form within thunderstorm
clouds when upward moving air keeps pellets of frozen water from falling. The pellets grow
larger as drops of very cold water hit them and freeze. Eventually the balls of ice become so
large and heavy that they fall to the ground as hailstones. The largest documented hailstone
weighted more than one and a half pounds! Scientists estimate that it reached a speed of more
than 80 mph as it fell toward Earth.

27. Sleet
Sleet is like slush falling from the sky. Sleet forms when raindrops freeze into ice as they fall
to the ground. They are usually smaller and wetter than hailstones.

28. •What determines the type of
precipitation that will be experienced
in a particular place?

29. 1. Convection
Convection occurs when the Earth's surface, within a conditionally unstable or moist atmosphere,
becomes heated more than its surroundings, leading to significant evaporation. Convective rain, or
showery precipitation, occurs from convective clouds, e.g., cumulonimbus or cumulus congestus. It falls
as showers with rapidly changing intensity. Convective precipitation falls over a certain area for a
relatively short time, as convective clouds have limited horizontal extent. Most precipitation in
the tropics appears to be convective; however, it has been suggested that stratiform precipitation
thunderstorms. Graupel and hail indicate convection. In mid-latitudes, convective precipitation is
associated with cold fronts (often behind the front), squall lines, and warm fronts in very moist air.

30. 2. Stratiform
Stratiform precipitation is caused by frontal systems
surrounding extratropical cyclones or lows, which form when warm and
often tropical air meets cooler air. Stratiform precipitation typically falls
out of nimbostratus clouds.

31. 3. Orographic
Orographic or relief rainfall is caused when masses of air pushed by wind are
forced up the side of elevated land formations, such as large mountains. The lift
of the air up the side of the mountain results in adiabatic cooling, and ultimately
condensation and precipitation. In mountainous parts of the world subjected to
relatively consistent winds (for example, the trade winds), a more
moist climate usually prevails on the windward side of a mountain than on
theleeward (downwind) side. Moisture is removed by orographic lift, leaving
drier air on the descending (generally warming), leeward side where a rain
shadow is observed.

32. Tropical Weather

33. Much of the equatorial belt within the tropical climate zone experiences
hot and humid weather. There is abundant rainfall due to the active
vertical uplift or convection of air that takes place there, and during
certain periods, thunderstorms can occur every day. Nevertheless, this belt
still receives considerable sunshine, and with the excessive rainfall,
provides ideal growing conditions for luxuriant vegetation. The principal
regions with a tropical climate are the Amazon Basin in Brazil, the Congo
Basin in West Africa and Indonesia.

35. The Inter- Tropical
Convergence Zone (ITCZ)

36. The Inter-Tropical Convergence Zone (ITCZ) appears as a band
of clouds consisting of showers, with occasional thunderstorms,
that encircles the globe near the equator. The solid band of
clouds may extend for many hundreds of miles and is sometimes
broken into smaller line segments. The ITCZ follows the sun in
that the position varies seasonally. It moves north in the northern
summer and south in the northern winter. The ITCZ (pronounced
"itch") is what is responsible for the wet and dry seasons in the
tropics.

38. How Typhoons are formed?

39. Typhoons start off as tropical thunderstorms. The strong winds pull in moisture from the
oceans.

40. The thunderstorms convert the moisture into heat. The heat causes more air to flow to
the centre of the storm causing evaporation.

41. All the heat and air flow toward the eye creating the typhoon.

42. Storm Surge

43. What is storm Surge?
A storm surge is a rise in sea level that occurs
duringtropical cyclones, intense storms also known astyphoons
or hurricanes. The storms produce strong winds that push the
water into shore, which can lead to flooding. This makes storm
surges very dangerous for coastal regions.

45. Factors that affect the
height of a storm surge

46. A storm surge is primarily caused by the relationship between the winds and the ocean’s surface. The
water level rises where the winds are strongest. In addition, water is pushed in the direction the winds
are blowing. The rotation of the Earth causes winds to move toward the right in the Northern
Hemisphere and toward the left in the Southern Hemisphere—a phenomenon known as the Coriolis
effect. If a cyclone develops in the Northern Hemisphere, the surge will be largest in the right-forward
part of the storm. In the Southern Hemisphere, the surge will be largest in the left-forward part of the
cyclone.
Another factor contributing to storm surge is atmospheric pressure. Atmospheric pressure is the force
exerted by the weight of air in the Earth’s atmosphere. The pressure is higher at the edges of a cyclone
than it is at the center. This pushes down the water in the outer parts of the storm, causing the water to
bulge at the eye and eye wall—where the winds have helped add to the rise in sea level.
More factors contribute to the strength of a storm surge as the dome of water comes ashore. The water
level can reach as high as 10 meters (33 feet) if the storm surge happens at the same time as high tide.
The slope of the land just off the coast also plays a part: Water will more easily flood a shallow coast
than a steep one.

47. Sources:
http://www.econet.org.uk/weather/whatis.html
http://www.climateandweather.net/world-weather/factors-that-influence-weather.html
http://www.econet.org.uk/weather/wind.html
http://www.econet.org.uk/weather/temp.html
http://www.econet.org.uk/weather/sun.html
http://www.weatherwizkids.com/weather-climate.htm
http://www.econet.org.uk/weather/pressure.html
http://www.econet.org.uk/weather/humid.html
http://www.econet.org.uk/weather/cloud.html
http://scied.ucar.edu/webweather/clouds/how-clouds-form
http://www.weatherwizkids.com/weather-clouds.htm
http://www.econet.org.uk/weather/ppt.html
http://www.eo.ucar.edu/basics/wx_2_b.html
https://en.wikipedia.org/wiki/Precipitation_types
http://www.ecoca.ro/meteo/tutorial/climate/Older/Tropical_Climate.html
http://www.srh.noaa.gov/jetstream/tropics/itcz.htm
http://education.nationalgeographic.com/encyclopedia/storm-surge/
http://www.nws.noaa.gov/om/hurricane/resources/surge_intro.pdf
http://www.theglobeandmail.com/news/world/explainer-how-are-typhoons-
formed/article15373372/

48. The End