Climate and Weather [EARTH SCIENCE]

• Weather refers to the day-to-day changes or patterns in the atmosphere at a particular place and time. It is determined by air temperature, air pressure, wind strength, and type of clouds.
• The Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) which is under the Department of Science and Technology (DOST) is responsible for issuing daily weather reports.
• Climate is defined as the cumulative patterns of weather in a particular place over a long period of time. In the early 20th century, a German scientist named Wladimir Koppen developed one of the most widely used classification systems.
• The Koppen System categorizes climate into five main types, which can be further divided into subcategories: Tropical, Dry, Temperate, Continental, Polar
• Tropical- humid and average temperature above 18°C (64°F)
• Arid (Dry)- evaporation exceeding precipitation with constant water deficiency throughout the year
• Temperate- humid or warm and hot summers and mild winters with average temperatures between -3°C (27°F) and 18°C (64°F)
• Continental - humid and warm summers with the average temperature of warmest month exceeding 10°C (50°F) and cold winters with an average temperature of the coldest month below -3°C (27°F)
• Polar - extremely cold winters with an average temperature of the warmest summer month below 10°C (50°F)
• Factors affecting climate

  • temperature
  • precipitation
• temperature

  • latitude
  • altitude
  • ocean currents
• latitude

  • A measure of the distance north and south of the equator
  • Areas near the equator have warm climates because they receive direct sunlight.
• altitude

  • The elevation or distance above mean sea level
  • Temperatures in higher places are low.
• ocean currents

  • An ocean current is a stream of water that flows in a definite path.
  • Cold ocean water currents mean cooler coastal lands.
• precipitation

  • prevailing winds
  • mountain ranges
• Different prevailing winds carry different amounts of moisture, affecting the amount of precipitation in a region
• Mountain ranges act as a barrier to prevailing winds

  • Windward side (facing the wind) receives moist air and has more precipitation
  • Leeward (away from the wind) side has little precipitation
• WEATHER- describes the condition of the atmosphere in a particular time (cool and dry, humid, windy, rainy, or stormy)
• CLIMATE- average weather in a region over a number of years or usually decades (tropical)
• CLOUDS - little drops of water or ice hanging in the atmosphere. A ceilometer measures the height of clouds.
• cloud types

  • cirrus
  • cirrocumulus
  • cirrostratus
  • stratus
  • cumulus
  • cumulonimbus
• descriptive name

  • cirrus: Mare's tails
  • cirrocumulus: Mackerel sky
  • cirrostratus: Bed sheet clouds
  • stratus: High fogs
  • cumulus: Cauliflowers
  • cumulonimbus: Thunderheads
• description

  • cirrus: thin, feathery
  • cirrocumulus: small patches of white
  • cirrostratus: thin, white sheets
  • stratus: low, gray blanket
  • cumulus: flat-bottomed, white puffy
  • cumulonimbus: mountains of heavy, dark clouds
• Weather changes are caused by the movements of bodies of air called air masses. Air masses could be warm or cold. As air masses move away from the source region, their temperature and humidity gradually change. When two air masses meet, a front is formed.
• Types of front

  • cold front
  • warm front
• Cold Front. It occurs when cold air is advancing into warm air. In a cold front setup, the boundary between the cold and warm air masses is relatively steep, typically causing the warm air in front of it to rise rapidly. This rising air creates energetic, billowing cumulonimbus clouds leading to showers and thunderstorms. After the cold front passes, skies typically clear rapidly and temperatures

  
• Warm Front. It occurs when cold air mass is retreating and warm air is advancing. With a warm front, the boundary between warm and cold air is more gradual than that of a cold front, which allows warm air to slowly rise and clouds to spread out into gloomy, overcast stratus clouds. Precipitation ahead of a warm front typically forms into a large shield of steady rain or snow. After the warm front passes, fair and milder weather is typical, however, a cold front is likely not far behind.

  
• The unequal heating of Earth’s surface forms a large global wind system. In areas near the equator, due to the direct rays of the sun, Earth’s surface heats

  up rapidly. As a result, warm air rises and moves towards the poles. At the

  poles, cooler air sinks and moves toward the equator. This movement produces the global pattern of air circulation.
• Global winds do not move directly from north to south or vice versa. Because

  of Earth’s rotation, the paths of the winds shift in relation to the surface.

  • Winds on the Northern Hemisphere curve to the right.
  • Winds on the Southern Hemisphere curve to the left.
• This apparent shift in the path of any object moving above the Earth’s surface

  due to the rotation of the Earth is called the Coriolis Effect. It also causes

  the air currents in cyclones to spin.
• Differences in air pressure from one location to another cause winds to move from high-pressure areas to low-pressure areas. Air pressure depends on the density of the air. Less dense air exerts less pressure. Air pressure has a great effect on the weather. When warm air rises, it produces an area of low pressure.
• Cyclone. It is a low pressure area with rising warm air. In a cyclone, cooler air moves in and takes the place of the rising warm air. The air currents begin to spin. Winds spiral around and into the center of the cyclone. They move in a counterclockwise direction in the Northern Hemisphere and a clockwise direction in the Southern Hemisphere. Cyclones usually cause rainy, stormy weather.
• Anticyclone. It is a high pressure area containing cold and dry air. Windows spiral around and out from the centers of anticyclones. They move in a clockwise direction in the Northern Hemisphere. The anticyclones usually bring in clear, dry, and fair weather.
• Typhoons, hurricanes, and cyclones are the same weather phenomenon. The only difference is the geographic area where they occur. They are tropical cyclones with regionally specific names.
• • Typhoon. It is used only in the northwestern part of the Pacific Ocean.
  • Cyclone. It occurs in the south Pacific and the Indian Ocean.
  • Hurricane. It occurs in the northeastern part of the Pacific Ocean and the northern part of the Atlantic Ocean.
• In the western Pacific Ocean, low-pressure areas bring in typhoons, which are results of severe weather conditions from intense low pressure formation. Typhoons normally develop over warm ocean waters and rotate in a clockwise direction because of the coriolis effect. Typhoons are formed by the rising warm, moist air, followed by the cooler air that moves in and begins to spin. As air pressure drops, more air spins faster. The rapidly spinning, rising air forms a cylindrical wall of strong winds, clouds, and rainfall. Inside the wall, the air is calm. The calm center is called the eye.
• Since the Philippines is part of Southeastern Asia, it is affected by the southwesterly monsoons that usually begin in early May. Monsoon winds are seasonal winds that blow over the northern part of the Indian Ocean and flow over most of the surrounding areas. Monsoon winds may be accompanied by rain. Typhoons begin near the equator and move westward, gathering intensity and size.
• Tropical cyclones are classified as:

  • Tropical Depression has a maximum wind speed of less than 61 km per hour (kph)
  • Tropical Storm has a maximum wind speed of 62 kph to 88 kph
  • Severe Tropical Storm has a maximum wind speed of 89 kph to 117 kph
  • Typhoon has a maximum speed of 118 kph to 220 kph
  • Super Typhoon has a wind speed of at least 220 kph
• The location of the Philippines in the Pacific Ring of Fire and its tropical climate make it prone to typhoons. In the Philippines, tropical cyclones (typhoons) are called bagyo. Tropical cyclones entering the Philippine Area of Responsibility (PAR) are given local names by the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA), which also raises public storm signals when a typhoon enters or threatens the

  PAR. According to PAGASA, about 20 tropical cyclones enter the PAR each year.
• PAR refers to the designated area in the western North Pacific where PAGASA is tasked to monitor tropical cyclone occurrences. PAGASA issues tropical cyclone bulletins every 6 hours for all tropical cyclones within the PAR that are anticipated to make landfall within the Philippines, or every 12 hours when cyclones are not affecting land. PAGASA classifies tropical cyclones using five-level Public Storm Warning Signals (PSWS).