Transcript Unit 6: Weather & Climate

Presented by:
Beenish Zunnoon
AGENDA
Weather
Pakistan's weather
Measuring weather
Global warming
Climate
Thunderstorm
Factors affecting climate
Tornadoes
Worlds climate
Tropical cyclone
atmosphere
WEATHER

The state of the atmosphere at a given time
and place, with respect to variables such as
temperature, moisture, wind velocity, and
barometric pressure.

Can change rapidly.

Small geographical area.
WEATHER (cont)
The study of weather is meteorology.
Someone who studies weather is called a
meteorologist.
MEASURING
WEATHER
Measurement
Temperature
Air Pressure
Wind (direction)
Wind (speed)
Relative Humidity
Precipitation
Instrument
Thermometer
Barometer
Wind Vane
Anemometer
Hygrometer
Rain Gauge
CLIMATE
Climate is commonly defined as the weather
averaged over a long period of time.
The standard average period is 30 years.
Large geographical area.
It is determined by two main factors: temperature
and rainfall.
FACTORS AFFECTING CLIMATE
( temperature & rainfall)
Elevation (height)
Topography
(geography)
latitude
ocean currents
prevailing wind
direction
Elevation
Elevation is the distance above sea level.
The air pressure decreases as the distance increases
from the sea level.
The farther above sea level you are, the lower the
temperature will be.
latitude
Latitude measures how far you
are north or south of the equator.
Latitude determines the amount of solar energy received by that
region.
Regions close to the equator receive direct rays of the sun and
therefore are warmer.
At the areas closer to the poles, the suns rays are at an angle so these
areas receive less radiant energy and are cooler.
Ocean currents
Water in the ocean travels in paths
called currents.
The temperature of the water affects the temperature of the air above
it.
Ocean currents traveling away from the equator are warm, warming the
air above it.
Currents flowing toward the equator are colder, so the air masses,
moving over these currents, are cooled.
topology
The features of the land also influences the
climate.
The amount of rainfall in a region is affected by mountain ranges in that
area. Mountains cause air to rise. Rising air becomes less dense
allowing the condensation of water. rainfall occurs.
Air moving down the other side of the mountain becomes more dense.
Sinking air does not produce precipitation.
The leeward side, or side facing away from the wind, receives less
precipitation.
Prevailing winds
Prevailing winds are the winds
which blow more often from one
direction than another.
Winds can greatly affect the amount of precipitation an area receives
depending on the amount of moisture they are carrying.
These prevailing winds can move air masses from the ocean onto a
continent bringing moisture onto the continent. Or prevailing winds may
move air masses from continent to the ocean, moving drier air from the
continent. Prevailing winds affect the climate of an area.
EARTH’S CLIMATE
EARTH’S CLIMATE (cont)
Rainforests receive a lot of rain. The temperature stays warm in
the rainforest all year long.
Grasslands are typically found on the dry interior of continents.
Temperate forest contains moist climate which allows
leafy deciduous trees to thrive.
Deserts receive less rainfall than other tropical ecosystems but
are just as warm.
EARTH’S CLIMATE (cont)
Chaparral has wet-winters and dry-summers.
Tundra: Ocean winds in arctic coastal areas keep the
temperatures from being as severe as interior regions. A long,
chilly winter season is followed by a mild season.
Taiga: The forests of the taiga ecosystem survive despite long
and very cold winters. Summers are short and still quite cool.
ATMOSPHERE
The layer of air surrounding the Earth.
The atmosphere is commonly divided into the
troposphere, the stratosphere, and the
ionosphere.
Troposphere contains the majority of the
atmospheric mass and all of the atmospheric
water vapor, most weather events occur within
it.
The average composition of atmosphere is
79% nitrogen, 20% oxygen, 0.03% carbon
dioxide, and traces of rare gases.
Also present are atmospheric moisture,
ammonia, ozone, and salts and solid particles.
PAKISTAN’S WEATHER
Depending on the topography there is an
extreme variation in the temperature.
The country is essentially arid except for the
southern slopes of the Himalayas and the submountainous tract
PAKISTAN’S WEATHER (cont)
The controlling factors of the Pakistan's climate are
Sub-Tropical location that tends to keep the
temperature high, particularly in summer.
The oceanic influence of the Arabian Sea
that keeps down the temperature contrast
between summer and winter at the coast.
PAKISTAN’S WEATHER (cont)
Higher altitudes in the west and north that keep
the temperature down throughout the year.
The Monsoon winds that bring rainfall in
summer.
The Western Depression originating from the
Mediterranean region and entering Pakistan
from the west that brings rainfall in winter.
RAINFALL IN PAKISTAN
The major part of Pakistan experiences dry climate.
Humid conditions prevail but over a small area in the
north.
The whole of Sindh, most of Balochistan, the major part
of the Punjab and central parts of Northern Areas
receive less than 250 mm of rainfall in a year.
Northern Sindh, southern Punjab, north-western
Balochistan and the central parts of Northern Areas
receive less than 125 mm of rainfall.
RAINFALL IN PAKISTAN (cont)
True humid conditions appear after the rainfall increases to
750 mm in plains and 625 mm in highlands.
There are two sources of rainfall in Pakistan: the Monsoon
and the Western Depression. The former takes place from
July to September and the latter, December to March.
GLOBAL WARMING
What is Global Warming?
Global warming is the increase in the average
temperature of the Earth's near-surface air and
oceans in recent decades and Is projected to
continue.
Causes of Global Warming
Carbon Dioxide
Methane
Nitrous oxide
Deforestation
Effects Of Global Warming
Melting Of Glaciers
Sea level rise
Rise in temperature
Ocean Acidification
FUTURE OF NEW YORK CITY
FUTURE OF GLACIERS
TYPES
OF
STORMS
THUNDERSTORM
A thunderstorm, also called an electrical storm or
lightning storm
Thunderstorms form when significant
condensation— resulting in the production of a
wide range of water droplets and ice crystals—
occurs in an atmosphere that is unstable and
supports deep, rapid upward motion.
THUNDERSTORM (cont)
It generates lightning, thunder and is normally
accompanied by heavy rainfall.
Thunderstorms occur throughout the world, with
the highest frequency in tropical rainforest
regions where there are conditions of high
humidity and temperature.
TYPES OF STORMS
TORNADO
A tornado is a storm with a twist
 It is a violently rotating column of air which is in contact with
both a cumulonimbus cloud or a cumulus cloud base and the
surface of the earth.
 Tornadoes come in many sizes but are
typically in the form of a visible
condensation funnel, whose
narrow end touches the earth and is
often encircled by a cloud of debris.

TROPICAL CYCLONE
Also known as hurricane
A tropical cyclone is a meteorological term for a storm system
characterized by a low pressure system center and
thunderstorms that produces strong wind and flooding rain.
A tropical cyclone feeds on the heat released when moist air
rises and the water vapor it contains condenses
 They develop over large bodies of warm water, and lose their
strength if they move over land
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