Weather and climate

weather

weather

Refers to the conditions of the atmosphere, temperature, pressure and humidity of a place for a short period of time.

generally refers to day-to-day temperature and precipitation activity, whereas climate is the term for the average atmospheric conditions over longer periods of time

e.g.Too rainfallWind direction and strengthCloud cover and;sunshine

climate

climate

Is the average state of the atmosphere over a long period of time.

the weather averaged over a long period.

The standard averaging period is 30 years.

season

season

A season is a subdivision of the year, marked by changes in weather, ecology, and hours of daylight. Seasons result from the yearly revolution of the Earth around the Sun and the tilt of the Earth’s axis relative to the plane of revolution.

"Climate is what you expect, weather is what you get."

The main elements of the atmosphere that determine weather and climate at a given place are:

TemperaturePrecipitation (including humidity and

clouds)Air pressureWinds storms and;visibility

Doppler radar - in Virac, Catanduanes. The equipment, developed by the Japan Radio Co. (JRC), is the first facility in the world to use the Solid-State Meteorological Radar System technology, which has 95 percent accuracy.

visibility

Factors interacting to cause weather are:

Heat energyAir pressureWinds and;Moisture

How are typhoons formed?

Typhoons start off as tropical thunderstorms. The strong winds pull in moisture from the oceans. The thunderstorms convert the moisture into heat. The heat causes more air to flow to the center of the storm which causes more evaporation. All the heat and air flow toward the eye creating the typhoon.

Difference between weather and climate

Weather differs from climate due to:

Latitude – determines the angle at which the sun’s rays strike the earth’s surface and their effectiveness;

Distribution of lands and water;Winds;Altitude;Mountain barriers;Big semi-permanent high and low

pressure centers; ocean currents; andDifferent kinds of storms.

Combinations of these factors in different intensities change

temperature that makes weather different from climate.

temperature

temperature

The degree of hotness and coldness of a substance.

ThermometerShows that the amount of

change is different for different materials.

Temperature is the most important element of weather because weather changes are brought about by the change in temperature of the different parts of the atmosphere.

Temperatures in the continental climates differ according to where air masses that blow come from.

Large & dry continents = desertsMountains = cooler climatesoClimates in the cities are warmer than

open countries.

Water vapor

Water vapor in the air is humidity.Comes from the evaporation of: Oceans; Rivers;

Lakes; Soil; Plants; and Animals.Warm air can hold more moisture than

an equal volume of cold air. Why?

Relative humidity

The amount of moisture in the air or the percentage of the moisture the air can holds a definite temperature

Relative humidity

The relative humidity  of an air-water mixture is defined as the ratio of the partial pressure of water vapor (H2O)  in the mixture to the saturated vapor pressure of water  at a prescribed temperature.Relative humidity is normally expressed as a percentage and is calculated by using the following equation:

%100 w

w

e

e

Dry-bulb

a. 27°C

b. 20°C

c. 15°C

d. 17°C

e. 30°C

Relative Humidity

%

%

%

%

%

Wet-bulb

25°C

16°C

12°C

12°C

29°C

Based on the percentage relative humidity obtained tells when (a-b-c-d-e)1. It is driest2. It is warmest3. It is coldest4. Rain will soon fall

Air motion and Air pressure

Air moves either horizontally as wind or vertically as currents.

Winds and currents transfer heat from the equator to the poles.

Heat comes directly from the earth and indirectly from the sun.

Air has weight.

Cold Air1cm3 Warm air

1cm3

More molecules?

Denser?

Temperature and amount of water vapor determine the density of air. The weight of the air at any given place is Air Pressure.

It is measured by an instrument called barometer.

Mercurial barometer

The first mercurial barometer was made by Torricelli, a student of Galileo.

Aneroid barometer

If the pressure increases, the sides of the container bend inward. If air pressure decreases the sides bulge out again.

Can be used both for measuring air pressure and altitude above sea level. – Altimeter

The higher the altitude, the thinner the air, the lighter it becomes.

Which zone has the lowest and highest air pressure? Why?

Cool pole air flows toward the equator and forces warm air up in the upper atmosphere, warm

air flows toward the poles.

Air pressure is determined by:Altitude

- the higher you go, the lower the air pressure, as the amount of air molecules decreases.Temperature

- cold air has more air molecules than hot airWater vapor

Temperature and amount of water vapor determine the density of the air.

Local winds

Local winds

At daytime, air over land areas is warmer than air over bodies of water.

- Flow of air from the sea to land is called sea breeze

At night, land cools faster than water bodies. Sea air is warmer than land air. Sea air rises, land air takes its place. This is the Land Breeze.

The name of the wind tells where it originates.

Huge land and sea breezes are called monsoons. –seasonal winds.

Northeast monsoonOctober – FebruaryWinds blows from cooler continent to warmer

ocean.It comes from northern Asia and blows toward the

Pacific Ocean.Cold season – Philippines – cool, dry season to

the northern.Winter season – north temperate and polar areas.“Hanging Amihan”

Southwest monsoonWinds blows from cooler ocean to

warmer continent.It comes from the Pacific Ocean and

brings rainy and typhoon season to the Philippines.

Oceans winds bring in warm, moist air, therefore heavy rains and warm temperatures over the land

“Hanging Habagat”

Major wind systems of the

earth

Factors affecting the winds in the earth are:

The earth’s rotation, Pressure belts, Differences in topography and In the heating of air masses over land and water.

Ferrell's lawThe law that wind is deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.The force that deflects it is the Coriolis Force.

Wind system

DoldrumsTrade windsHorse latitudesPrevailing westerly winds and;

Polar winds

DoldrumsA region of hot air, low air pressure

and calm.Air currents move upward or

downward.

Trade windsSlanting windsBlow in form north and south toward

the doldrums

Horse latitudesA regions of high pressure between the

trade wind belts and westerlies.Air that rises in the doldrums sinks to the

earth.From the HPA of the horse latitudes, air

moves toward the equator and toward the poles.

If the equator has a LPA due to heat, the poles have high pressure areas due to their coldness. The cold polar winds move toward the sub-polar low pressure belts, turn to the east, according to ferrel’s law, and become the polar easterlies.

Prevailing westerliesMoves away from the horse latitudes

toward the sub-polar low belts, but they are turned to the east by the earth’s rotation. As they come from the west, they are called the westerlies