Weather and Climate Chapter 19

1. CHAPTER 19
WEATHER AND CLIMATE

2. WEATHER – describe the condition in the atmosphere at a particular
time, on a particular day in a particular place.
• CLIMATE - describes the average of all weather conditions in a
particular place over many many years, usually decades.

3. ELEMENTS OF WEATHER
• 1. TEMPERATURE – is the most important element of
weather as it influences humidity, precipitation, air
pressure, wind speed and direction,and cloud formation.
• 2.HUMIDITY – is the amount of water vapor present in
the atmosphere.
– RELATIVE HUMIDITY – refers to the ratio of moisture
actually present in the air compared to what the air
can hold at a given temperature.
– HYGROMETER – used to measure humidity.
3. ATMOSPHERIC PRESSURE - pressure exerted by air.

4. HIGH PRESSURE AREAS – areas where the air is thicker.
( produces a good weather )
LOW PRESSURE AREAS – areas where the air is not thick
( produces a bad weather )
• 4. WIND AND AIR MASSES
– WIND – moving air (continual rising and falling of
air)
- it blows from an area of high pressure to an area of
low pressure
2 GENERAL TYPES OF WIND
A. LOCAL WINDS – flow from any direction and
usually cover short distances.
B. GLOBAL WINDS - blow from a specific direction
and almost always travel longer distances.

6. MINOR WINDS
• 1. SEA BREEZE - the wind that blows
from the sea towards the land during
daytime.
• 2. LAND BREEZE – the wind that blows
from the land to the sea during the night.

8. AIR MASS - An air mass is a body of air that extends over a large area
and has nearly uniform temperature and humidity in any horizontal
direction.
When air masses meet, there is a mixing of cold and warm air, this
mixing will cause a disturbance in the atmosphere, and a thunderstorm
may result.
It may also result in FRONTS.

9. FRONT – 2 air masses that meet at a certain point.
TYPE OF FRONT ASSOCIATED WEATHER
1. COLD ( when a mass Short precipitation occurs quickly but
of cold air meets & may be heavy, more violent storms, rapid
replaces a mass of movement, cooler temperature
warm air)
2. WARM ( when a mass of Prolonged gentle precipitation, slow
warm air overtakes a cold movement, warm temperature
air mass & moves over it)
3. OCCLUDED ( cold front Complex weather, light rainshowers
overtakes a warm front & is maybe followed by thunder storm,
rushed upward) precipitation caused by rising warm air.
4. STATIONARY ( warm air Long periods of the same weather,
mass meets a cold air mass weather changes when front begins to
& no movement occurs ) move.

10. 5. CLOUD FORMATION
• Water vapor and dust are involve in cloud
formation.
• Clouds are formed as water condenses on
particles called condensation nuclei in the
atmosphere.

11. TYPES OF CLOUDS
• 1. CIRRUS - are thin and wispy.
 Formed at the highest altitudes usually between
6000 – 10 000 m above the surface of the earth.

12. 2. CUMULUS – are thick and puffy, with flat bottom. They look like
cotton balls piled together. They are generally low clouds and known
as ― fair weather‖ clouds.

13. STRATUS – are layered and sprea out over the whole sky like a
blanket. Gentle rain may produced by stratus clouds.

14. NIMBUS – ( rain ) dark and heavy rain cloud that is going to bring rain.

17. 6. PRECIPITATION – is the transfer of water from atmosphere back to
the earth’s surface. ( rain, snow, hail, sleet )
FORMS OF PRECIPITATION DESCRIPTION
1. RAIN formed when snow melts as it
falls
2. Snow Water vapor changes directly into
solid crystals
3. SLEET Snow melts and falls through
layers of cold air where it freezes
4. HAIL Sleet is pushed up and down in
the atmosphere until it grows
larger

18. snow

19. hail

20. WEATHER DISTURBANCES
• 1. THUNDERSTORM – is a small scale
weather system with lightning and
thunder, produced by cumulonimbus cloud
that has a funnel shape, usually producing
gusty winds, heavy rain and sometimes
hail.

21. 2. TROPICAL CYCLONE - is a low pressure system which generally
forms over the tropics with wind and thunderstorm activity.It comes
from Greek word KYKLOS w/c means ― cycling snake ‖.
• They are huge, violent whirlwinds that happen in many
parts of the earth.
• They are weather systems that rush in a spiral motion
from different diections to a low pressure center called
the ― eye of the storm ‖.

22. 1. TROPICAL DEPRESSION – tropical cyclones with maximum sustained
surface winds of less than 62kph.
• 2. TROPICAL STORM – tropical cyclone that reaches
wind of at least 62kph. ( name is given )
• 3. THYPOON – if winds reach 118kph
• HURRICANE – in Atlantic
– PAGASA – Philippine Atmospheric, Geophysical, Astronomical
Services Administration

23. SOUTHWEST MONSOON – ( HABAGAT ) comes from the word ―
mausim‖ which means seasonal wind. It si generally warm and dry bur
picks up moisture as it passes the warm waters Of Indonesian Sea and
moves toward the equator with a low pressure.This brings rain to many
parts of the Phil. From May to September.
• Northeast monsoon – ( amihan ) comes in October to February and
brings rain mostly in Mindanao.
• INTERTROPICAL CONVERGENCE ZONE (ITCZ ) – is the meeting
place of hot and cold tradewinds in the northern and southern
hemispheres. It may result in rain showers to heavy rains in
affected areas.

24. WEATHER INSTRUMENTS
• 1. BAROMETER – measures air pressure.
It was built by an Italian named Evagelista
Toricelli.

25. RAIN GUAGE – measures amount
of precipitation

26. THERMOMETER – measures air
temperature

27. LIGHTNING DETECTOR – it detects through radio frequency the
activity of a storm. It indicates the distance of a lightning, and whether
a storm is approaching or departing.

28. Psychrometer – measures relative
humidity.

29. WIND VANE – measures wind
speed

30. Weather balloon – it is sent into the atmosphere to note the weather
conditions at very high altitudes

31. Weather satellite – it takes and sends photographs of air movements
over large areas from the outer space.

32. CLIMATE CHANGE
• 1. EL NINO SOUTHERN OSCILLATION
– The term El Niño—Spanish for "the Christ Child"—was originally
used by fishermen to refer to the Pacific Ocean warm currents
near the coasts of Peru and Ecuador that appeared periodically
around Christmas time and lasted for a few months. Due to
those currents, fish were much less abundant than usual. At the
present time we use the same name for the large-scale warming
of surface waters of the Pacific Ocean every 3-6 years, which
usually lasts for 9-12 months, but may continue for up to 18
months, and dramatically affects the weather worldwide. best-
known for its association with floods, droughts and other
weather disturbances in many regions of the world, which vary
with each event

33. GREEN HOUSE EFFECT