This online textbook is a comprehensive resource for Tropical Meteorology. It is intended for use by undergraduate and early graduate students in Tropical Meteorology courses, forecasters, and others interested in the impacts of tropical weather and climate. Learn more about its unique features by clicking "Go".

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This chapter begins with an overview of energy balance and the global climate system. Various definitions of the tropics are presented. The role of the tropics in the global energy and momentum balance is presented. Atmospheric structure of temperature and humidity are discussed in terms of latitudinal variability. Pressure ranges and scales of atmospheric motion in the tropics are reviewed. Seasonal and geographic distribution and the diurnal cycle of surface temperature and the influencing factors are examined in detail. Finally, we review tropical air masses and climates.

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This chapter focuses on remote sensing—the primary method of observing weather and climate across the global tropics. Clouds and precipitation are observed by measuring microwave signals using ground-based radar; spaceborne radar; and satellite radiometers. Wind vectors across the ocean are estimated by satellite scatterometry; dust and volcanic ash are tracked using multispectral images; vegetation and soil moisture indices monitor land surface changes. A cloud radar profiles the atmosphere from space and GPS satellite signals are used to create soundings.

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The chapter begins with a review of the general principles of atmospheric motion including scale analysis of tropical motions. An overview of the general circulation of the atmosphere and ocean is presented including stratospheric general circulation. Special emphasis is given to the Hadley circulation including its maintenance, seasonal migration, northern and southern hemispheric differences, and comparison with midlatitude wind systems. Tropical circulations are examined in a theoretical framework as responses to heating at the equator. Regional monsoons, their conceptual models, seasonal evolution, and variability are explored. Modeling of the general circulation is examined in a focus section.

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This chapter presents an overview of major cyclical patterns that dominate tropical intraseasonal and interannual variability, including the impact on higher latitudes. The potential role of multidecadal oscillations in modulating these shorter cycles will be discussed. Characteristic atmospheric and oceanic patterns for the oscillations are presented and methods for tracking their evolution are described. Classical solutions for tropical waves are presented and the effects of moisture on these waves are discussed.

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Water vapor and precipitation are essential for life. Precipitation amount and frequency have tremendous socio-economic impact in tropical countries. The global energy and water cycles are driven by tropical heating and moisture transport. Learn how thermodynamic energy is used to distinguish between fair weather, stormy weather, and the effect of dry intrusions, such as the Saharan Air Layer. Explore tropical cloud formation and distribution; precipitation processes and classifications; the lifecycle of tropical squall lines, annual, seasonal, diurnal, and interannual cycles of tropical precipitation.

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This chapter examines energy exchanges from the surface through the troposphere. Latent heat, sensible heat, and momentum fluxes are examined at surface interfaces and over seasonal and diurnal cycles. The mixed layer is compared over the ocean, humid, and dry tropics. Boundary layer clouds are examined in terms of their connection to the sub-cloud layer properties. Comparisons are made between heat and moisture transport under a variety of convective modes. The trade wind inversion, its maintenance, and east-west structure across the tropical oceans are presented.

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In this chapter, we examine the wide-variety of synoptic weather systems that affect the tropics, including, tropical easterly waves, inertia-gravity waves, upper tropospheric troughs, subtropical cyclones, and monsoon depressions. Extratropical interactions, such as those caused by Rossby wave trains and the MJO, are examined. This chapter presents a review of thunderstorms and lightning. The structure, formation mechanisms, and hazards of mesoscale convective systems (squall lines, MCCs, and MCVs) are examined. The distribution of lightning globally and within mesoscale systems is examined. Mesoscale and local circulations, such as sea-breezes, are explored. The final section focuses on supercells, tornadoes, and waterspouts.

This chapter describes tropical cyclones, their history of naming conventions, seasonal and geographic variability and controls, and decadal cycles. The core and balance solutions for regions of the cyclone are examined. Genesis is explored in depth. Intensity scales and satellite interpretation techniques are described. Links between inner core dynamics and changes in intensity are explored. Limits on intensity are considered. Factors that influence motion are described. Extratropical transition is described in terms of structural changes, preceding mechanisms, and impact on high latitudes. The final section describes societal impacts.

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The chapter first describes the challenges of tropical weather forecasting. Then, we examine types of observations and weather analysis techniques used by tropical forecasters. The last three sections focus on numerical weather prediction including: the fundamentals, comparisons of statistical and dynamical models, ensemble techniques, cumulus convection, tropical cyclone prediction, and forecast verification and validation. The Australian-Indonesian monsoon focus section applies various analysis and forecasting techniques. Finally, tropical cyclone forecasters describe their forecast routine.

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