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At the tropopause (the point in altitude where the lowest part of Earth’s atmosphere, the turbulent troposphere, transitions into the more stable stratosphere), which is located at about nine miles up, bands of 200 mile-per-hour air currents flow around the world while periodically meandering north and south. These air currents are known as jet streams. [...]

Since at least the late 1970’s, trees in the Amazon have been growing faster despite the fact that climbing vines (lianas), which grow on trees as parasites and sap their energy, have also increased in number and spatial extent. This growth means that the rate at which each hectare (2.47 acres) in the Amazon takes [...]

Getting a break from exposure to hot temperatures is important for preventing heat related illnesses. While people usually associate extreme daytime temperatures with heat stroke, if it does not cool sufficiently during the night, the body will not get a break from the heat. In North America over the last 50 years, average nighttime low [...]

The June 15, 1991 eruption of Mt. Pinatubo, which sits on the island of Luzon in the Philippines, injected between 31 and 44 billion pounds of sulfur dioxide (SO2) into Earth’s stratosphere (the second layer of the Earth’s atmosphere). This layer of SO2 circled the globe in about three weeks, and by the end of [...]

Convective available potential energy (CAPE) is a measure of how much energy is available for storm development (CAPE is measured by the number of joules present in a kilogram of air). Generally, the hotter and more humid conditions are, the more CAPE is present. A collection of atmospheric conditions, including some CAPE, are necessary for [...]

The North Atlantic Oscillation (NAO) is a cyclical change in the difference in atmospheric pressure between a low pressure center around Iceland and a high pressure center around the Azores Islands in the North Atlantic. When this difference in pressure is larger (i.e. the low pressure center is especially low and the high pressure center [...]

The North Atlantic Oscillation (NAO), which is part of a large system known as the Arctic Oscillation, is a cyclical change in the difference in atmospheric pressure between a low pressure center around Iceland and a high pressure center around the Azores Islands in the North Atlantic. When this difference in pressure is larger (i.e. [...]

The North Atlantic Oscillation (NAO) is a cyclical change in the difference in atmospheric pressure between a low pressure center around Iceland and a high pressure center around the Azores Islands in the North Atlantic. When this difference in pressure is larger (i.e. the low pressure center is especially low and the high pressure center [...]

Atmospheric carbon dioxide (CO2) levels have risen from 280 parts per million in pre-industrial times to around 385 parts per million today. The rate of this rise has varied from year to year. The two phases of the El Niño Southern Oscillation Cycle (ENSO), El Niño (positive) and La Niña (negative), appear to have a [...]

Prior to European settlement, Longleaf Pine forests covered a 140 million square mile area that runs along the Atlantic and Gulf Coasts from Southern Virginia to Texas. Frequent, low-intensity fires, which traditionally happened every two to four years and would sweep across the forest floor like a broom without killing the Pine trees themselves, keeping [...]

Map makers (also known as cartographers) and astronomers site the tropics as the region between the latitudes of 23.5 degrees north and 23.5 degrees south, or the two points where the sun is directly overhead on the summer and winters solstices respectively. Climatologists define the tropics slightly differently, with the basis of the definition relying [...]

Atmospheric carbon dioxide (CO2) levels have risen from about 280 parts per million in pre-industrial times to around 390 parts per million today. During winter in temperate deciduous forests, the days are too cold and short for trees to efficiently make food, and as a result, the trees are dormant during this time of year. [...]

In the last fifty years, the temperature of the upper 3000 meters of the ocean (which is about 70 percent of the World’s ocean water), rose by 0.07 degrees Fahrenheit. While this number may seem small, the same amount of energy it would take to raise the? world’s ocean heat content by just 0.18 degrees [...]

Woody climbing vines, which in the Amazon Rainforest are known as lianas, account for only about five percent of the total plant mass in the rainforest, but up to 40 percent of the total leaf production. Lianas can produce so many leaves because instead of using energy to build hard, lignin rich tree trunks, they [...]

Terrestrial Net Primary Production (NPP) is the total amount of vegetation that the Earth’s land plants make by using sunlight, carbon dioxide (CO2), and water. Total NPP is influenced by climatic conditions such as atmospheric CO2 levels, rainfall amounts and patterns, cloud cover, and temperature. Factors that limit NPP include longer winters, increases in cloud [...]

The more water in the atmosphere, the less easily sweat evaporates from your body, and the harder it is to keep your body at a comfortable temperature. The dewpoint temperature is one of the best indicators of how “uncomfortable” hot weather is, and when the dewpoint temperature exceeds 65 degrees Fahrenheit, most people consider the [...]

Just to the east of the Cascades, Ponderosa and Lodgepole Pine forests transition into the Central Oregon Prairie, or the Central Oregon Steppe. This prairie is dotted with Sagebrush, various grasses, and Western Juniper trees, which are short and compact trees known for producing Juniper berries. Juniper trees have become increasingly common over the last [...]

The Walker Circulation is a circular belt of air that moves around the tropical Pacific. The warm moist air of the trade winds moves westward from the coast of South America. As these winds move, the air travels upward, cools, and rain falls. This drier and cooler air then moves in the upper levels of [...]

Rising temperatures in many parts of the United States have caused an increase in evaporation and drying of the soil. This is especially true in the Southwestern United States where there has been a persistent drought since about 2000, despite there being no real change in the amount of rainfall.  At the same time, there [...]

Researchers found that since the mid-1980’s, the length of the wildfire season (the period of the year when it is dry and hot enough for fires to happen) in the forests of the Western United States has grown 78 days longer as a result of earlier snowmelt and increased spring and summer temperatures. These trends, [...]