Weather describes the atmospheric condition at a place over a short duration of time. You could say, it is the result of atmosphere responding to uneven heating by the sun. Another term that related to weather is climate. Climate is the distribution of weather over a long period of time.
Heating by the Sun contributes a major part to atmospheric condition. There are two ways of heat distribution in general:
- Vertical heat transport
Solar heating of the Earth’s surface makes the atmosphere convectively unstable, generating vertical air currents to develop. This affects the clouds looking puffy, shows and thunderstorms to form in warm air masses.
- Horizontal heat transport
The Earth is not flat. It receives more sunlight at the equator compared to northern and southern part. Resulting horizontal temperature differences to arise. Causing air pressure differences, leading to wind that brings heat from tropics to high latitude.
In collusion, both horizontal and vertical heat transport directions in the atmosphere causes everything that we perceive as weather.
In general, one would describe weather as sunny, cloudy, or rain. Such explanations are conclusion of many different variables that contribute to this atmospheric condition.
- Air humidity
Air humidity is a measure of the quantity of water vapor in the air. Approximately one percent of Earth’s total water content is suspended in the atmosphere as water vapor, precipitation or clouds. Humidity is a measure only of the vapor content.
Precipitation is any type of water that forms in the atmosphere and then drops onto the surface of the Earth. Water vapor in the atmosphere is visible as clouds and fog. Clouds eventually get too full or water vapor. Then the precipitation turns into liquid (rain) or solid (solid).
- Air pressure
The uneven solar heating affect temperature differences, causing high and low pressure areas to develop. The horizontal heat transport by wind from low to high latitudes is strongly influenced by rotation of the Earth. It prevents the wind from flowing directly from high pressure to low pressure, thus causes the wind to flow around high and low pressure centers.
- Air temperature
Temperature differences is caused by uneven heating of the Earth. In turn, causes air currents or wind to develop and then move the heat from an area where there is more heat or high temperature to another area with less heat or low temperature.
- Speed and direction of the wind
Wind refers to any flow of air relative to the Earth’s surface in a roughly horizontal direction. The ultimate cause of earth’s wind is solar energy. When sunlight hit the Earth’s surface, it heats the surface unevenly. Resulting differences in air pressure with provide force that drives the air from one point to another. This is what we know as wind.
- Amount and kind of cloud cover
Cloud cover means the fraction of the sky obscured by cloud when observed from a particular location. There are three main types of cloud: cirrus, stratus, and cumulus. Big puffy clouds could reflect radiation of the Sun’s energy, cooling a hot day. But on a different day, it could also trap some heat beneath them. Insulating and warming the ground below.
The six factors above are result from the interaction of four basic physical elements. They are the Sun, the Earth’s atmosphere, the Earth itself and natural landform on the Earth’s surface. As the main energy of the Earth, the Sun plays the biggest role. The sun causes convection within the atmosphere, which in turn affects weather and climate.
Weather affects almost everything. From traffic, clothes to wear, up to power outages. To understand and able to predict weather is necessary. Therefore, checking it daily using application or other electronic media is only logic.
Weather forecasting is the implementation of science and technology to predict the conditions of the atmosphere at a certain time and place. It is done by collecting quantitative data about the current state of the atmosphere at a given place and using meteorology to project how the atmosphere will change.
Humans has tried to forecast the condition since thousands of years ago. However, the formal practice started in 19th century. When the technology was not as advance as today, the human-only attempt based mainly upon changes in barometric pressure, current weather conditions and sky conditions. Now it uses computer-based models that calculate many atmospheric factors with human’s involvement still needed.
Weather Forecasting Equipment
Many equipment is used to forecast weather. Here are some of them:
- Doppler radar
Doppler radar is the meteorologist’s window into observing severe storms. It detects all types of precipitation, the rotation of thunderstorm clouds, airborne tornado debris, and wind strength and direction.
- Weather satellite
Weather satellites monitor Earth from space. It gathers observational data to be analysed. There are two types of weather satellites. First, polar orbiting satellites which covers the entire earth asynchronously. It takes six to seven detailed images a day. Second is geostationary satellites which remain at the same place and takes images of the entire Earth as frequently as every 30 minutes. Besides these two, United States agency called National Oceanic and Atmospheric Administration (NOAA) uses one more satellite named Deep Space Climate Observatory. It monitors solar storms and space weather.
Radiosonde uses to measure variables such as air pressure, temperature, relative humidity, wind speed and its speed. It is carried into stratosphere, which is the second lower layer of atmosphere at 12-50 km from ground level using weather balloon.
- Automated surface-observing systems
Automated surface-observing systems or ASOS report data about weather conditions on surface of the Earth. It sends data from various locations. The data including sky conditions, surface visibility, precipitation, temperature and wind up to 12 times an hour.
Weather and Climate Operational Supercomputer System can process data gathered by other equipment. It then works its numeral forecast models that uses equations along with new and past weather data. Resulting forecast guidance for meteorologists.
AWIPS stands for Advance Weather Information Processing System. It is a computer processing system that combines data from all tools above into a graphical interface. The interface then used by forecasters to analyse data, prepare and issue forecast, watches, warnings. AWIPS is used by United States’ National Oceanic and Atmospheric Administration (NOAA). NOAA also utilize all the equipment mentioned in this list.
Overall, weather is the response of uneven heating of the Earth by the sun. As the atmosphere “attempt” to reduce the resulting differences in temperature. We then describe the weather conditions as sunny, cloudy, windy, rainy and snowy.