WEATHER - DAILY CHANGES IN THE EARTH’S ATMOSPHERE CLIMATE - LONG-TERM, SYSTEMATIC CHANGES IN THE EARTH’S CLIMATE OF A MULTI-YEAR SCALE

WEATHER VARIABLES -PRESSURE -TEMPERATURE -DEW POINT -HUMIDITY -WIND SPEED / DIRECTION -CLOUD COVER

PRESSURE IS THE FORCE IN WHICH THE ATMOSPHERE ABOVE YOU EXHURTS ON YOU *2

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UNITS FOR MEASURING PRESSURE *1

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PRESSURE DECREASES AS ALTITUDE INCREASES *1

PRESSURE GRADIENTS (OR VARIATIONS IN PRESSURE) CAUSE THE WIND TO BLOW FROM HIGH PRESSURE TO LOW PRESSURE AREAS *1

TEMPERATURE IS THE MEASUREMENT OF THE HEAT ENERGY IN THE AIR HEAT IN THE ATMOSPHERE *7

WATER VAPOR INFLUENCES MUCH OF THE ATMOSPHERE’S ENERGY, ESPECIALLY DURING PHASE CHANGES HEAT IN THE ATMOSPHERE *6

HEAT OF FUSION – ENERGY REQUIRED TO CHANGE 1 GRAM FROM SOLID TO LIQUID HEAT OF VAPORIZATION – ENERGY REQUIRED TO CHANGE 1 GRAM FROM LIQUID TO GAS HEAT ENERGY VOCABULARY *6

HEAT OF FUSION WATER = 80 CALORIES/GRAM HEAT OF VAPORIZATION WATER = 540 CALORIES/GRAM HEAT ENERGY VOCABULARY *6

HEAT ENERGY VOCABULARY *6

WATER REQUIRES MORE ENERGY THAN MOST MATERIALS TO RAISE ITS TEMPERATURE BEFCAUSE IT HAS A HIGH SPECIFIC HEAT SPECIFIC HEAT OF WATER *6

THE AMOUNT OF WATER VAPOR IN THE AIR ABSOLUTE HUMIDITY – THE WEIGHT OF THE WATER VAPOR IN A VOLUME OF AIR RELATIVE HUMIDITY – THE PERCENTAGE OF WATER VAPOR IN THE SURROUND AIR

THE AMOUNT OF WATER VAPOR IN THE AIR *8

DEW POINT- THE TEMPERATURE AT WHICH AN AMOUNT OF WATER VAPOR WILL BEGIN TO CONDENSE FROM A GAS TO A LIQUID STATE CONDENSATION OF WATER *9

CONDENSATION OF WATER SATURATED – REACHED THE MAXIMUM POTENTIAL HOLDING CAPACITY UNSATURATED – HAVING THE ABILITY TO ABSORB MORE VAPOR

CONDENSATION OF WATER THE HIGHER THE TEMPERATURE, THE MORE WATER VAPOR THAT CAN BE HELD IN THE SURROUNDING AIR

A PSYCHROMETER MEASURES HUMIDITY AND DEWPOINT BY MEASURING THE CURRENT AIR TEMPERATURE COMPARED TO THE SATURATED AIR TEMPERATURE PSYCHROMETER *10

Psychromotor Dry Bulb Temperature The Dry Bulb temperature, usually referred to as air temperature, is the air property that is most common used. When people refer to the temperature of the air, they are normally referring to its dry bulb temperature. Wet Bulb Temperature The Wet Bulb temperature is the temperature of complete saturation. This is the temperature indicated by a moistened thermometer bulb exposed to the air flow. Wet Bulb temperature can be measured by using a thermometer with the bulb wrapped in wet muslin. The rate of evaporation from the wet bandage on the bulb, and the temperature difference between the dry bulb and wet bulb, depends on the humidity of the air. The evaporation is reduced when the air contains more water vapor. The wet bulb temperature is always lower than the dry bulb temperature but will be identical with 100% relative humidity (the air is at the saturation line).

Combining the dry bulb and wet bulb temperature in a psychrometric diagram or Mollier chart, gives the state of the humid air. Lines of constant wet bulb temperatures run diagonally from the upper left to the lower right in the Psychrometric Chart.psychrometric diagram or Mollier chartPsychrometric Chart

CONVECTION CREATES RISING AIR CURRENTS THROUGH LESS DENSE (WARMER) AIR RISING OVER THE MORE DENSE (COLDER) AIR CONVECTION *11

HARRIS HILL, NEW YORK *11

CONDENSATION OF WATER CLOUDS FORM WHEN RISING AIR COOLS (AS IT EXPANDS) WHICH CAUSES THE AIR THE AIR TEMPERATURE TO FALL TO ITS DEW POINT.

STRATUS CLOUDS *12

CUMULUS CLOUDS *12

CIRRUS CLOUDS *12

CONDENSATION OF WATER &feature=related

Isotherms Isotherms are lines of constant or equal temperature. They are often used on weather maps by meteorologists to give a large scale view of temperatures across the U.S. If you have ever looked at a weather map in a newspaper, the isotherms are used to divide the color-filled temperatures

For example, in the map below, temperatures in the 60's may be represented by a yellow color, while temperatures in the 70's may be represented by an orange color. The line that divides the yellow from the orange is the isotherm. All of the locations between the 60 degree isotherm and the 70 degree isotherm will have a temperature between 60 and 70 degrees.

Isobars Isobars are lines of constant or equal pressure on a weather map. They can be used to find areas of low or high pressure over a broad area (like the U.S.), and they can tell us how intense the system may be. On weather maps, you may have noticed areas that have a large “L” or “H” over a region with lines circling around them. The lines circling them are isobars

Generally the lowest pressure is where precipitation is most likely to fall, and high pressures are usually associated with clear and sunny conditions. Where the isobars are close together, windy conditions may be expected. Elongated areas of low pressure on surface and upper air weather maps are called "troughs" and elongated areas of high pressure are called "ridges."

So why do we use isotherms and isobars? Isotherms and isobars allow us to view large scale processes much more easily than looking at the raw data from individual weather stations itself. Figure C: Raw DataFigure D: Isotherms Added